docs: document master and keycloak API branches

[hariclerry]

Description

• Documents the differences between the master and keycloak branches in the wallet API.
• Resolves Document authentication and branch differences between master and keycloak #607

What kind of change(s) does this PR introduce?

- Added the deployed route for each branch.
- Documented the authentication method used by each branch.
- Explained the shared PostgreSQL database implications.
- Added guidance for selecting the correct target branch.
- Noted that contributors should confirm the target branch with maintainers.

• Enhancement
• Bug fix
• Refactor

Please check if the PR fulfils these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Breaking change

Does this PR introduce a breaking change?

• No

Other useful information

None

[hariclerry]

The documentation update is ready for review. It documents the differences between the master and keycloak branches, including routes, authentication, shared database usage, and branch-targeting guidance.

Please review the content and let me know if any information is inaccurate, incomplete, or needs correction. Additional guidance is welcome before merging.

[Kpoke]

Was something meant to be here?

Also. maybe update docker-compose to support keycloak as well, and the documentation on how to go about that, including getting tokens, so a user can just run docker compose and have everything set up locally