patman: Add Cover-letter-cc tag to Cc cover letter to people

The cover letter is sent to everyone who is on the Cc list for any of
the patches in the series. Sometimes it is useful to send just the cover
letter to additional people, so that they are aware of the series, but
don't need to wade through all the individual patches.

Add a new Cover-letter-cc tag for this purpose.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
diff --git a/tools/patman/README b/tools/patman/README
index 86d366f..9922f2a 100644
--- a/tools/patman/README
+++ b/tools/patman/README
@@ -182,6 +182,10 @@
 	Sets the cover letter contents for the series. The first line
 	will become the subject of the cover letter
 
+Cover-letter-cc: email / alias
+	Additional email addresses / aliases to send cover letter to (you
+	can add this multiple times)
+
 Series-notes:
 blah blah
 blah blah
@@ -263,7 +267,13 @@
 afleming.
 
 If you have a cover letter it will get sent to the union of the CC lists of
-all of the other patches.
+all of the other patches. If you want to sent it to additional people you
+can add a tag:
+
+Cover-letter-cc: <list of addresses>
+
+These people will get the cover letter even if they are not on the To/Cc
+list for any of the patches.
 
 
 Example Work Flow