git-submodule.sh: add some comments

Add a couple of comments in a few functions where they were missing.

Signed-off-by: Roy Eldar <royeldar0@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: Roy Eldar

git-submodule.sh

@@ -418,6 +418,7 @@ cmd_set_branch() {
 	default=
 	branch=
 
+	# parse $args after "submodule ... set-branch".
 	while test $# -ne 0
 	do
 		case "$1" in
@@ -466,6 +467,7 @@ cmd_set_branch() {
 # $@ = requested path, requested url
 #
 cmd_set_url() {
+	# parse $args after "submodule ... set-url".
 	while test $# -ne 0
 	do
 		case "$1" in
@@ -604,6 +606,7 @@ cmd_status()
 #
 cmd_sync()
 {
+	# parse $args after "submodule ... sync".
 	while test $# -ne 0
 	do
 		case "$1" in