- "Toggle Refill minor mode.
-With prefix arg, turn Refill mode on if arg is positive, otherwise turn it off.
+ "Toggle automatic refilling (Refill mode).
+With a prefix argument ARG, enable Refill mode if ARG is
+positive, and disable it otherwise. If called from Lisp, enable
+the mode if ARG is omitted or nil.
+
+Refill mode is a buffer-local minor mode. When enabled, the
+current paragraph is refilled as you edit. Self-inserting
+characters only cause refilling if they would cause
+auto-filling.