+ "Toggle reverting buffer when the file changes (Auto Revert mode).
+With a prefix argument ARG, enable Auto Revert mode if ARG is
+positive, and disable it otherwise. If called from Lisp, enable
+the mode if ARG is omitted or nil.
+
+Auto Revert mode is a minor mode that affects only the current
+buffer. When enabled, it reverts the buffer when the file on
+disk changes.