automv: add some context for the tests

automv: add some context for the tests

--- a/tests/test-automv.t	Mon Feb 15 16:40:06 2016 +0000
+++ b/tests/test-automv.t	Mon Feb 15 16:44:30 2016 +0000
@@ -1,3 +1,5 @@
+Tests for the automv extension; detect moved files at commit time.
+
   $ cat >> $HGRCPATH << EOF
   > [extensions]
   > automv=