Up-to-date compile constraints instructions

[TimMonko]

References and relevant issues

Each time I need to update constraints, I go to the github action, check the workflow, find the bash script, forget how it works, etc.
After walking @carlosmariorr through this tonight, I wanted to finally make the update to the docs.
re: napari/napari#9052

Description

This updates the constraints instructions to bring it up to date, both the uv pip command itself and now that we have the compile_constraints.sh script. Namely:

1. commands that can be used for napari-bot
2. how to use compile_constraints.sh and what args are passed to it (and how to format them)
3. how to manage the files, namely differences between pyprpoject.toml and version_denylist.txt