Add troubleshooting for "I can get data from my Origin, but not through Caches"

[jhiemstrawisc]

FYI @aowen-uwmad -- there were lots of small linting errors in the original branch that didn't pass my pre-commit locally, hence the larger diff. Do you have pre-commit installed wherever you're drafting these docs?

[aowen-uwmad]

@jhiemstrawisc , no, I don't have pre-commit installed.
Do I just need to install that package? Or do I need to do some sort of configuration to get it to read whatever it needs to?

[jhiemstrawisc]

I think the usual song and dance is:

$ python3 -m pip install pre-commit

# From the root of the Pelican repo:
$ pre-commit install

Anytime you commit after that point, the pre-commit hooks will run to handle things like formatting markdown, running a spell checker, etc. Any changes it makes will prevent the commit from applying, but you'll be able to review what it did and then re-commit.

[jhiemstrawisc]

Failing tests are the result of flaky unit tests -- this diff only touches docs, so the only CI we really care about here is linting.