patch 8.1.2212: cannot see the selection type in :reg output

Problem:    Cannot see the selection type in :reg output. (Ayberk Aydın)
Solution:   Add c/l/b. (Christian Brabandt, closes #5110, closes #4546)
diff --git a/runtime/doc/change.txt b/runtime/doc/change.txt
index 9b8155c..eda0d6c 100644
--- a/runtime/doc/change.txt
+++ b/runtime/doc/change.txt
@@ -999,9 +999,13 @@
 			delete and yank) ({.%#:} only work with put).
 
 							*:reg* *:registers*
-:reg[isters]		Display the contents of all numbered and named
-			registers.  If a register is written to for |:redir|
-			it will not be listed.
+:reg[isters]		Display the type and contents of all numbered and
+			named registers.  If a register is written to for
+			|:redir| it will not be listed.
+			Type can be one of:
+			"c"	for |characterwise| text
+			"l"	for |linewise| text
+			"b"	for |blockwise-visual| text
 
 
 :reg[isters] {arg}	Display the contents of the numbered and named