This PR removes all minutes and agendas in `meetings/`. These were
previously hosted in this repository, but we found that it makes things
somewhat more complex with respect to CI configuration and merge
permissions to have both small, CI-less changes to the text in
`meetings/` as well as changes to everything else in one repository.
The minutes and agendas have been split out into the repository at
https://github.com/bytecodealliance/meetings/, with all history
preserved. Future agenda additions and minutes contributions should go
there as PRs.
Finally, this PR adds a small note to our "Contributing" doc to note the
existence of the meetings and invite folks to ask to join if interested.
f1b821e16f