[Docs] [V1] [Hybrid] Add new documentation re: contributing mamba-based models

[tdoublep]

Purpose

Update documentation to reflect latest state of mamba support, and add some instructions to help people contribute new mamba-based models in the future.

cc @heheda12345

Test Plan

n/a

Test Result

n/a

Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[gemini-code-assist]

Code Review

This pull request updates the documentation to reflect the current state of Mamba model support. It adds a comprehensive guide for contributors on how to add new Mamba-based models, covering different scenarios and providing helpful code references. The v1 usage guide is also updated to reflect the latest supported models and to clarify the status of prefix caching. The documentation changes are clear, accurate, and will be very helpful for the community. The updates are consistent with the provided code context. Overall, this is a great contribution to improving the project's documentation.

[tdoublep]

Does anyone know if using gh-file with line numbers will render as-intended?

[heheda12345]

Nice job!!!! Can you also mention that MambaCacheManager is only for v0 and don't need to add related code and other if v0 code path for new models?

[tdoublep]

Can you also mention that MambaCacheManager is only for v0 and don't need to add related code and other if v0 code path for new models?

Done

[heheda12345]

LGTM! Very helpful doc.