Create Release Blog

Why is this change being made?

This creates a new blog with Middleman for Releases. That means there are two blogs within the repo:

1. The Marketing Blog
2. Releases

All posts categorized as "releases" are moved to the releases blog.

This change is being made to separate releases posts from marketing posts. The content and deployment of these posts are managed by different teams. Plus, the audience is different. Release posts are also a blocker for separating the blog into its own repository. This MR will solve the blocker and allow work to continue on creating a separate repository for the marketing blog.

Cheat Sheet for blog post authors

If you have a blog post MR in progress when this MR is deployed, you will have to make some adjustments to your MR. Here is a cheat sheet on how to do that. https://docs.google.com/document/d/1GdQuaYGd89tV5O8YEx7pVIIBqhrYvaY7h6gMDjVVjU0/edit?usp=sharing

What is changed?

For Middleman to have multiple blogs defined in config.rb, you must add blog.prefix and blog.name to each blog definition. blog.prefix adds a prefix to all links, templates references, and source paths. This means blog posts must live within their defined blog directory in the source directory. The source/posts directory is no longer valid. This is the primary reason why this MR touches over 1000 files. All posts have been moved!

Here is an overview of what changed:

1. config.rb is updated to generated two blogs named blog and releases
2. All posts categorized as releases are moved to /source/releases/posts
3. All remaining posts are moved to /source/blog/posts
4. All blog includes are updated to draw posts from both blogs
5. Links to the Releases blog category are changed from /blog/categories/releases/ to /releases/categories/releases/
6. Redirects are added for all releases posts since their URL is changed from blog/post-url/ to releases/post-url
7. Rakefile - linting of blog posts updated with new directory location of blog posts
8. Release generator is updated with new directory past of release posts

What to test

Here's what needs to be checked before merging

• Do the redirects work?
• Do release posts still get pulled into the homepage?
• Do release posts still get pulled into the blog page?
• Create a test release post to verify process till works
• Are release posts included in the sitemap?
• Does the release generator work?
• Check that atom feeds for the blog are correct and include release posts

Does this MR meet the acceptance criteria?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what

Related #6120 (closed)