Update runtime files

runtime/doc/repeat.txt

@@ -1,4 +1,4 @@
-*repeat.txt*    For Vim version 8.2.  Last change: 2020 Apr 26
+*repeat.txt*    For Vim version 8.2.  Last change: 2020 May 14
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -126,6 +126,11 @@ q{0-9a-zA-Z"}		Record typed characters into register {0-9a-zA-Z"}
 			recorded macro and the yank will overwrite the
 			recorded macro.
 
+			Note: The recording happens while you type, replaying
+			the register happens as if the keys come from a
+			mapping.  This matters, for example, for undo, which
+			only syncs when commands were typed.
+
 q			Stops recording.  (Implementation note: The 'q' that
 			stops recording is not stored in the register, unless
 			it was the result of a mapping)
@@ -137,7 +142,7 @@ q			Stops recording.  (Implementation note: The 'q' that
 			used.
 			The register is executed like a mapping, that means
 			that the difference between 'wildchar' and 'wildcharm'
-			applies.
+			applies, and undo might not be synced in the same way.
 			For "@=" you are prompted to enter an expression.  The
 			result of the expression is then executed.
 			See also |@:|.