SubmittingPatches: mention the usage of real name in Signed-off-by: lines

Especially with something that is supposed to hopefully have some legal
value down the line if somebody starts making noises, it really would be
nice to have a real person to associate things with. Suggest this in the
SubmittingPatches document.
Signed-off-by: NMiklos Vajna <vmiklos@frugalware.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/SubmittingPatches

@@ -222,6 +222,9 @@ D-C-O.  Indeed you are encouraged to do so.  Do not forget to
 place an in-body "From: " line at the beginning to properly attribute
 the change to its true author (see (2) above).
 
+Also notice that a real name is used in the Signed-off-by: line. Please
+don't hide your real name.
+
 Some people also put extra tags at the end.
 
 "Acked-by:" says that the patch was reviewed by the person who