How to merge author information.

Signed-off-by: Heikki Hokkanen <hoxu@users.sf.net>

doc/gitstats.pod

@@ -81,6 +81,10 @@ Q: I have files in my git repository that I would like to exclude from the stati
 
 A: At the moment the only way is to use L<git-filter-branch(1)> to create a temporary repository and generate the statistics from that.
 
+Q: How do I merge author information when the same author has made commits using different names or emails ?
+
+A: Use git .mailmap feature described in B<MAPPING AUTHORS> of L<git-shortlog(1)>.
+
 =head1 EXAMPLES
 
 =over