Put tags/categories to Blog pages

[t-kikuc]

What would you like to be added:

Tag or/and categorize Blog pages so that users can easily search.

Why is this needed:

Currently, https://pipecd.dev/blog/ contains some kinds of articles (e.g. announcements, best practices)
Users cannot easily find the pages they're looking for.

[t-kikuc]

[FYI] We can use Hugo's feature for them.

for example:

---
date: 2023-02-07
title: "PipeCD best practice 02 - control plane on ECS"
...
categories: ["Example"]
tags: ["Control Plane", "AWS"]
---

Categories and Tags will be shown like this: