docs: add release notes notifying change of default branch to `develop`

Additional Information

Add a release note notifying the new default branch as develop.

[x] I have performed a self-review of my own code (note: N/A)
[x] I have commented my code, particularly in hard-to-understand areas (note: N/A)
[x] I have added or updated relevant unit/integration/functional/e2e tests (note: N/A)
[x] I have made corresponding changes to the documentation
[x] I have assigned this pull request to a milestone (for repository code-owners and collaborators only)