Add a documentation page on error handling

There's some major gaps around error handling in the official docs, especially painful because the whole ecosystem relies on them - library users are often instructed to use MonadError/ApplicativeError error handling code, but it's not present in the documentation

• Add a page on ApplicativeError/MonadError (one page, likely)
  • Either on that page or on its own page, provide a "cookbook" of common error handling examples

This is mentioned in #1801, but I thought it was worth calling out as its own issue