Add out_sharding docstrings to linear layer call methods

[jackopenn]

What does this PR do?

Add out_sharding docstrings to linear layers (Linear, LinearGeneral, Einsum) call methods.

Fixes # (issue)

Checklist

• This PR fixes a minor issue (e.g.: typo or small bug) or improves the docs (you can dismiss the other checks if that's the case).
• This change is discussed in a Github issue/discussion (please add a link).
• The documentation and docstrings adhere to the documentation guidelines.
• This change includes necessary high-coverage tests. (No quality testing = no merge!)