Fix reference to changed parameter name in doc comment for checkPos
Fix reference to changed parameter name in doc comment for checkPos

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