Add a how-to guide on ASDF version warnings and one on re-downloading metadata ASDF files

[Cadair]

Two things that happened as part of the 1.10 cycle that I think warrant how-to guides are:

• ASDF version warnings: We should cover what the warnings that are emitted when opening an asdf file with out of date versions are and what they mean (i.e .you need to update). This guide should also recommend that people make new environments often.
• Re-downloading ASDF files: This guide should elucidate that the DKIST data center will from time-to-time update the ASDF files and you should re-download them (with Fido.fetch(..., overwrite=True) until we have a way to detect stale local files DCS-4811)