We have a lot of dead links in IOOS 1.2 guidance

[mwengren]

Review https://ioos.github.io/ioos-metadata/ioos-metadata-profile-v1-2.html for link rot or improved links to add.

• [ ] some ERDDAP dataset links have changed (PacIOOS)
• [ ] NCEI wiki links are dead, xref: https://github.com/ioos/ioos-metadata/issues/23#issuecomment-1518047196
• [ ] ?

[MathewBiddle]

Maybe we should add a link checker to the build process?

See html-proofer Ruby gem as one way.