README: update git location and add mailing list information

Now that a Mailing list is set up, update the README to point to it
and mention the new maintained git location for this fork.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/README b/README
index 0de60c1..fdeed07 100644
--- a/README
+++ b/README
@@ -8,7 +8,21 @@
 
 See file ./INSTALL for building and installation instructions.
 
-Main git repository:
+Original development was done at:
   git://kernel.ubuntu.com/jk/sbsigntool.git
 
+The current maintained fork resides at:
+
+  https://git.kernel.org/pub/scm/linux/kernel/git/jejb/sbsigntools.git/
+
+And a very low volume mailing list for bugs and patches is setup at
+
+ sbsigntools@groups.io
+
+Thanks to groups.io policies, non-members can post to this list, but
+non-member postings are moderated until released (so they won't show
+up immediately).  The list archives are available:
+
+ https://groups.io/g/sbsigntools/topics
+
 sbsigntool is free software.  See the file COPYING for copying conditions.