Document functions, function args and return value

[avdv]

Is your feature request related to a problem? Please describe.
Public facing functions should be properly documented.

Describe the solution you'd like
Buildifier emits warnings for these (see https://github.com/bazelbuild/buildtools/blob/main/WARNINGS.md#function-docstring-header) by default.

Currently, we have disabled buildifier lint warnings for these.

We want to enable these warnings and fix the problems reported.

Describe alternatives you've considered

Additional context
See #2323