Adding the bulletins page for changelog/announcements

[shrivaths16]

Description

Adding bulletin.md file to the docs folder, filling it with the latest release details and adding the appropriate file to the index.rst to display the same.

Types of changes

• [ ] Bugfix
• [ ] New feature
• [ ] Refactor / Code style update (no logical changes)
• [ ] Build / CI changes
• [ ] Documentation Update
• [ ] Other (explain)

Does this address any currently open issues?

[list open issues here]

Outside contributors checklist

• [ ] Review the guidelines for contributing to this repository
• [ ] Read and sign the CLA and add yourself to the authors list
• [ ] Make sure you are making a pull request against the develop branch (not main). Also you should start your branch off develop
• [ ] Add tests that prove your fix is effective or that your feature works
• [ ] Add necessary documentation (if appropriate)

Thank you for contributing to SLEAP!

:heart: