Add some example filter scripts

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

filters/commit-links.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+# This script can be used to generate links in commit messages - the first
+# sed expression generates links to commits referenced by their SHA1, while
+# the second expression generates links to a fictional bugtracker.
+#
+# To use this script, refer to this file with either the commit-filter or the
+# repo.commit-filter options in cgitrc.
+
+sed -re '
+s|\b([0-9a-fA-F]{8,40})\b|<a href="./?id=\1">\1</a>|g
+s| #([0-9]+)\b|<a href="http://bugs.example.com/?bug=\1">#\1</a>|g
+'