Add docs for SelectionState
Add docs for SelectionState

tzuhsiulin/prosemirror,adrianheine/prosemirror,tzuhsiulin/prosemirror,salzhrani/prosemirror,jacwright/prosemirror,tzuhsiulin/prosemirror,salzhrani/prosemirror,kiejo/prosemirror,adrianheine/prosemirror,kiejo/prosemirror,mattberkowitz/prosemirror,kiejo/prosemirror,salzhrani/prosemirror,mattberkowitz/prosemirror,jacwright/prosemirror,adrianheine/prosemirror