Update the release cycle

[rajarshimaitra]

Description

Follow the bdk main release process, expect making intermediate release candidate. Add other issue templates. Add Development_cycle notes. Update PR template to include changelog section. Update changelog to include instruction of new change log format.

Notes to the reviewers

Please re-check the minor_release.md file where I updated the release process without rc creation.

Checklists

All Submissions:

• [x] I've signed all my commits
• [x] I followed the contribution guidelines
• [x] I ran cargo fmt and cargo clippy before committing