Update squashmigration docs to also mention circ dep errs (refs #23337)

    you can delete them.

Note that model interdependencies in Django can get very complex, and squashing

may occasionally result in an optimized migration that doesn't work or is

impossible to run. When this occurs, you can re-try with ``--no-optimize``, but

please `file a bug report <https://code.djangoproject.com/newticket>`_ either

way detailing the models and their relationships so we can improve the

optimizer to handle your case.

may result in migrations that do not run; either mis-optimized (in which case

you can try again with ``--no-optimize``, though you should also report an issue),

or with a ``CircularDependencyError``, in which case you can manually resolve it.

To manually resolve a ``CircularDependencyError``, break out one of

the ForeignKeys in the circular dependency loop into a separate

migration, and move the dependency on the other app with it. If you're unsure,

see how makemigrations deals with the problem when asked to create brand

new migrations from your models. In a future release of Django, squashmigrations

will be updated to attempt to resolve these errors itself.

Once you've squashed your migration, you should then commit it alongside the

migrations it replaces and distribute this change to all running instances