generate-cmdlist.sh: avoid selecting synopsis at wrong place

In "common" man pages there is luckily no "NAME" anywhere except at
beginning of documents. If there is another "NAME", sed could
mis-select it and lead to common-cmds.h corruption. So better nail it
at beginning of line, which would reduce corruption chance.
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

generate-cmdlist.sh

@@ -14,7 +14,7 @@ sort |
 while read cmd
 do
      sed -n '
-     /NAME/,/git-'"$cmd"'/H
+     /^NAME/,/git-'"$cmd"'/H
      ${
             x
             s/.*git-'"$cmd"' - \(.*\)/  {"'"$cmd"'", "\1"},/