docs: update Guide Using the Local Server

[henryh0x1]

Pages Page: https://jan.ai/guides/using-server/

Success Criteria Content that should be covered

• [ ] Overall guide of Using the Local Server
• [ ] Guides on how to use the Jan application, with GIFs. For end users who are directly using Jan.
• [ ] Related keywords should be updated.
• [ ] Related images should be compressed.

Include:

• How to turn on server in settings
• How to access server docs vial 1337/docs
• Warning about how api-reference is outdated (we should probably turn this page off for now)
• Warning about how other in app features (like threads chatting ux) might be broken while using server

Additional context TBD