Documentation: Note file formats send-email accepts

Signed-off-by: Todd Zullinger <tmz@pobox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-send-email.txt

@@ -19,6 +19,19 @@ The header of the email is configurable by command line options.  If not
 specified on the command line, the user will be prompted with a ReadLine
 enabled interface to provide the necessary information.
 
+There are two formats accepted for patch files:
+
+1. mbox format files
++
+This is what linkgit:git-format-patch[1] generates.  Most headers and MIME
+formatting are ignored.
+
+2. The original format used by Greg Kroah-Hartman's 'send_lots_of_email.pl'
+script
++
+This format expects the first line of the file to contain the "Cc:" value
+and the "Subject:" of the message as the second line.
+
 
 OPTIONS
 -------