* doc/emacs/maintaining.texi (VC Directory Commands): Document
vc-dir-ignore.
(@code{vc-dir-mark-all-files}). With a prefix argument, mark all
listed files and directories.
+@item G
+Add the file under point to the list of files that the VC should
+ignore (@code{vc-dir-ignore}). For instance, if the VC is Git, it
+will append this file to the @samp{.gitignore} file. If given a
+prefix, do this with all the marked files.
+
@item q
Quit the VC Directory buffer, and bury it (@code{quit-window}).