Update headings and guidance about headings.

docs/contribute/stage-documentation-changes.md

@@ -14,7 +14,7 @@ Create a fork of the Kubernetes documentation repository as described in
 
 {% capture steps %}
 
-### Staging from your GitHub account
+## Staging from your GitHub account
 
 GitHub provides staging of content in your master branch. Note that you
 might not want to merge your changes into your master branch. If that is
@@ -32,7 +32,7 @@ the master branch.
 
         https://<your-username>.github.io
 
-### Staging a pull request
+## Staging a pull request
 
 When you create a pull request, either against the master or &lt;vnext&gt;
 branch, your changes are staged in a custom subdomain on Netlify so that
@@ -47,7 +47,7 @@ Wait for the **deploy/netlify** check to complete. To the right of
 **deploy/netlify**, click **Details**. This opens a staging site where you
 can see your changes.
 
-### Staging locally using Docker
+## Staging locally using Docker
 
 You can use the k8sdocs Docker image to run a local staging server. If you're
 interested, you can view the
@@ -66,7 +66,7 @@ web server:
 1. View your staged content at
 [http://localhost:4000](http://localhost:4000){: target="_blank"}.
 
-### Staging locally without Docker
+## Staging locally without Docker
 
 1. [Install Ruby 2.2 or later](https://www.ruby-lang.org){: target="_blank"}.