New blog posts

General MR

Summary

Adds 2 new blog posts for 2.0: breaking changes and new features

Previews:

• https://repo1.dso.mil/big-bang/bigbang/-/blob/2-0-changes-blog/blog/2-0-breaking-changes.md
• https://repo1.dso.mil/big-bang/bigbang/-/blob/2-0-changes-blog/blog/2-0-new-features.md

Closes #1468 (closed)

blog/.pages

 nav:
+  - 2.0 New Features: 2-0-new-features.md
+  - 2.0 Breaking Changes: 2-0-breaking-changes.md
   - Big Bang 2.0: big-bang-2-0.md