Add some doc FIXMEs
Add some doc FIXMEs

salzhrani/prosemirror,tgecho/prosemirror,bengler/prosemirror,adrianheine/prosemirror,tzuhsiulin/prosemirror,mattberkowitz/prosemirror,tzuhsiulin/prosemirror,bengler/prosemirror,adrianheine/prosemirror,kiejo/prosemirror,tzuhsiulin/prosemirror,mattberkowitz/prosemirror,kiejo/prosemirror,tgecho/prosemirror,salzhrani/prosemirror,adrianheine/prosemirror,ProseMirror/prosemirror-markdown,kiejo/prosemirror,jacwright/prosemirror,salzhrani/prosemirror,jacwright/prosemirror