Add section about deploying with now to the docs (gatsbyjs#3641)

* Add section to the deploy docs page for deploying to now

* Add section to the deploy docs page for deploying to now

* Add install code snippet

* Update deploy-gatsby.md

docs/docs/deploy-gatsby.md

@@ -9,6 +9,7 @@ title: "Deploying Gatsby"
 * [GitHub Pages](/docs/deploy-gatsby/#github-pages)
 * [GitLab Pages](/docs/deploy-gatsby/#gitlab-pages)
 * [Heroku](/docs/deploy-gatsby/#heroku)
+* [Now](/docs/deploy-gatsby/#now)
 
 ## Netlify
 
@@ -245,6 +246,25 @@ Finally, add a `static.json` file in the root of your project to define the dire
 }
 ```
 
+## Now
+
+In order to deploy your Gatsby project using [Now](https://zeit.co/now), you can do the following:
+
+1. Install the Now CLI
+
+`npm install -g now`
+
+2. Install a node server package (such as `serve`, or `http-server`)
+
+`npm install --save serve`
+
+3. Add a `start` script to your `package.json` file, this is what Now will use to run your application:
+
+
+`"start": "serve public/"`
+
+4. Run `now` at the root of your Gatsby project, this will upload your project, run the `build` script, and then your `start` script.
+
 ## Debugging tips
 
 ### Don't minify HTML