Docs: Add mentee selection process (#5920)

* Docs: Add mentee selection process

Signed-off-by: Saswata Mukherjee <saswataminsta@yahoo.com>

* Update docs/contributing/mentorship.md

Co-authored-by: Lucas Servén Marín <lserven@gmail.com>
Signed-off-by: Saswata Mukherjee <saswataminsta@yahoo.com>

* Address feedback

Signed-off-by: Saswata Mukherjee <saswataminsta@yahoo.com>

* Apply suggestions from code review

Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>
Signed-off-by: Saswata Mukherjee <saswataminsta@yahoo.com>

* Address full-time mentee + feedback

Signed-off-by: Saswata Mukherjee <saswataminsta@yahoo.com>

* Apply suggestions from doc review

Co-authored-by: Lucas Servén Marín <lserven@gmail.com>
Signed-off-by: Saswata Mukherjee <saswataminsta@yahoo.com>

Signed-off-by: Saswata Mukherjee <saswataminsta@yahoo.com>
Co-authored-by: Lucas Servén Marín <lserven@gmail.com>
Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>

docs/contributing/mentorship.md

@@ -63,7 +63,7 @@ In order to allow mentees to share the knowledge their learned and allow them to
 
 ## For Mentors
 
-This section explains some process around selecting mentees (TBD) and [retrospective](#retrospective) process.
+This section explains processes around selecting mentees and conducting [retrospectives](#retrospective).
 
 ### Retrospective
 
@@ -82,4 +82,43 @@ The example retrospective process looks as follows:
 
 ### Mentees Selection
 
-TBD
+This section is to help guide mentors, old and new, on how to select mentees for Thanos mentorship projects. It details recommendations and steps for this entire process.
+
+#### Process
+
+We follow these steps when selecting mentees for any given project:
+
+1. After your project has been proposed to a particular mentorship program like LFX or GSoC, ensure that it is discoverable by potential mentees during the application period by sharing it on the relevant GitHub issue. You could also optionally share this on the [#thanos-dev slack channel](https://cloud-native.slack.com/archives/CL25937SP), [Twitter](https://twitter.com/ThanosMetrics), and even during Thanos Contributor Hours.
+2. Wait for the mentee application period to end and log into the relevant portal for the mentorship in order to view mentee applications. You can refer to the relevant documentation that you will receive to familiarize yourself with the portal, application format, and **selection deadlines**. Additional reference: [LFX Mentor docs](https://docs.linuxfoundation.org/lfx/mentorship/mentors/review-mentee-applications-and-tasks), [GSoC mentor guide](https://google.github.io/gsocguides/mentor/).
+3. Discuss with your co-mentors and shortlist roughly 30% of the mentees that you've found to be suitable by referring to their applications, which can consist of things like CVs, proposals, and "statement of purpose" type questions. Refer to [recommendations](#recommendations) for what to keep in mind while shortlisting.
+4. Send an email with a few extra questions to get to know these 30% potential mentees even more. You can refer to the `thanos-io@googlegroups.com` mailing list for a list of such questions and the email format from past mentorships. Make sure to add mentee emails to `bcc` and your co-mentors and `thanos-io@googlegroups.com` to `to`. Set a deadline for the responses.
+5. Once you receive replies from most of them, review again with your co-mentor and shortlist candidates that you would now like to interview.
+6. Conduct 20-minute interviews (refer to [recommendations](#recommendations) for what to keep in mind during these interviews) of the shortlisted mentees to get to know them even better and finally select a single person.
+7. Send an email to the selected mentee asking for confirmation and if they are happy with this.
+8. Once they reply, fill out the selection form in the relevant portal! :)
+
+#### Recommendations
+
+During mentee selection for our various mentorship programs, we want to follow some best practices to ensure that the mentorship is a fruitful experience for both mentees and mentors. A large part of ensuring this is selecting the most suitable candidate for the mentorship!
+
+This process is hard and requires time, as it involves holistically looking at mentorship applications and trying to ascertain if they would be able to benefit from this mentorship and ideally become a contributor, maintainer, or even new hire into the respective mentor's company in near future.
+
+We have been able to distill some learnings from several past mentorship programs, which are listed here as recommendations to mentors:
+
+* Encourage mentees interested in applying by asking them to look through our issues and try to work on one in which they would learn a bit about the codebase! There is no better proof of their motivation to work with us than seeing (meaningful) activity in the open-source project before the selection period.
+* Allocate some time upfront for this process, as you might have a lot of mentee applications to look through.
+  * If possible, book some time on your calendars and discuss the selection process with co-mentors in a particular quarter beforehand.
+* Try to have some prerequisites in mind while shortlisting an application of a potential mentee (CV/questions/proposal/interview),
+  * It is preferable to have mentees from historically underrepresented communities in tech, to ensure diverse contributors in Thanos.
+  * The mentee should be able to allocate enough time to the mentorship.
+    * Thus, having prior important commitments like a full-time job or large educational course load can lead to mentees not having enough time for the mentorship, even if they claim to commit to working > 30hrs a week. This could manifest as mentees not having enough energy to think about a project, skipping meetings, and not being able to utilize the time mentors can spend with them. It is hard to help them in such case. So it is better to practically judge the amount of work a mentee would be able to balance before selecting them.
+    * Generally, we expect our mentees to be university/college students who would be able to balance both the mentorship and a moderate amount of course load. Commitments larger than this would need to be treated with some caution. Generally, it's only ok to have a full-time job only for more senior engineers who understand how to organize their work, be transparent about the mentorship with their employer, etc.
+      * In case the mentee is employed full-time, asking for some form of proof (letter/forwarded email from manager) that their employer approves of them working on this mentorship is preferable.
+  * It is preferable for the mentee to have at least one prior contribution to Thanos or its dependencies that affect it indirectly. Such prior contributions demonstrate a willingness to engage with the community and independence from the potential mentee.
+    * However, the contribution should not be a minimal effort one, such as a typo/grammar fix or variable name change. While these are valued contributions, they cannot effectively demonstrate mentee effort. A better indicator would be some change to the code or documentation. Note that this contribution doesn't need to be in a merged or finalized state and can be open.
+  * The mentee should have access to a stable internet connection over which they can attend regular video calls with mentors (can be ensured during a 20-minute interview).
+    * As most of the discussions (meetings/issues/reviews/code comments) are conducted in English, the mentee should be able to communicate well (verbally and in written) in English (first/second language).
+  * The mentee should have some form of local development environment setup that they can operate which would not require the mentor to constantly debug the mentee's environment while working on the project.
+    * This is hard to ensure fully, but generally the mentee should be working on linux/linux VM/macOS/, so most generic GNU/BSD commands are compatible.
+    * The mentee should have basic git, bash, and programming knowledge.
+    * They should be using a common code editor with IDE functionality for Golang, e.g. VSCode, Goland etc, that they can operate comfortably for the duration of mentorship. The editor should allow them to easily navigate code and lookup definitions across large codebases as this makes it easier to pair program and share knowledge with them.