Reorganizing stuff

[kspurgin]

• create year subdirectories inside Meetings and re-file meeting notes in those subdirectories
• interfile chat transcripts with the meeting notes in year subdirectories
• standardize meeting note/agenda file names as: YYYY-MM-DD.md to support correct sorting of meetings and chat transcripts
• alphabetize participants list
• note new co-convener responsibility agreement in co-convener schedule
• update convener info in README
• find/replace across repo to update links to meeting notes that changed with reorganizing into year directories