Commented guess as to what the undocumented markmarker attribute does

Svante Lidman commented on the MarkFollowing:markmarker and MarkPrevious:markmarker remarking that the attribute's name does not describe accurately what it does. I'm assuming this is the intended function.
Merge pull request #1 from Elite6809/patch-1

Commented guess as to what the undocumented markmarker attribute does