Document Reported-by in SubmittingPatches

Randy pointed out that the Reported-By tag should be documented with the
others in SubmittingPatches.
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/SubmittingPatches

@@ -405,7 +405,14 @@ person it names.  This tag documents that potentially interested parties
 have been included in the discussion
 
 
-14) Using Tested-by: and Reviewed-by:
+14) Using Reported-by:, Tested-by: and Reviewed-by:
+
+If this patch fixes a problem reported by somebody else, consider adding a
+Reported-by: tag to credit the reporter for their contribution.  Please
+note that this tag should not be added without the reporter's permission,
+especially if the problem was not reported in a public forum.  That said,
+if we diligently credit our bug reporters, they will, hopefully, be
+inspired to help us again in the future.
 
 A Tested-by: tag indicates that the patch has been successfully tested (in
 some environment) by the person named.  This tag informs maintainers that