Summary

PR #1092 added Pylock.select() and PylockSelectError but docs/pylock.rst was not updated.

This PR:

• Adds select to the Pylock autoclass :members: directive so the method's docstring renders in the docs
• Adds PylockSelectError to the exceptions section
• Adds a brief usage example showing pylock.select() in the existing code block

Test plan

• nox -s docs builds without warnings
• select() method appears in the rendered Pylock class documentation
• PylockSelectError appears in the exceptions section