Typo in "Maintainer's Guide" and Minor Documentation Improvements

[TyagiRajat]

There are a few minor issues in the Stardoc documentation that need to be addressed:

Typo: The heading "Maintaner's guide" should be corrected to "Maintainer's guide."
Link Check: Verify that all links, especially the badge and those referencing external documentation (e.g., Starlark), are correct and functional.
Headings Consistency: Review the documentation headings to ensure consistent use of heading levels (e.g., using ## for all main sections).
Skydoc Deprecation Link: Confirm that the "Skydoc Deprecation" link is working and provides the intended information.