Add Description how to ignore findings to User Guide

[ckunki]

In rare cases you may need to disable a particular finding reported by one of the tools employed by the PTB.

A typical example is when importing all PTB's Nox sessions in your noxfile.py.

from exasol.toolbox.nox.tasks import *

Causing ruff to report error "F403 unused import".

In this case this we want to ignore the finding and keep the import to make
the PTB's Nox sessions available in our project.

This is achieved by appending a comment to the code line

from exasol.toolbox.nox.tasks import *  # noqa: F403

See
https://docs.astral.sh/ruff/configuration/

[ArBridgeman]

@ckunki We've started a page for this already. Maybe this should be added upon or moved to a better location:
https://exasol.github.io/python-toolbox/main/user_guide/features/formatting_code/troubleshooting.html#the-automatic-formatting-is-doing-x-but-we-shouldn-t-do-that-because-of-y

If you keep it where it is, it might be useful to link this from there to this page:
https://exasol.github.io/python-toolbox/main/user_guide/troubleshooting.html