Start 1.6.6.X maintenance track

Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/RelNotes-1.6.6.1.txt

+Git v1.6.6.1 Release Notes
+==========================
+
+Fixes since v1.6.6
+------------------
+
+ * http-backend was not listed in the command list in the documentation.
+
+Other minor documentation updates are included.
+
+--
+exec >/var/tmp/1
+O=v1.6.6-4-gd828fdb
+echo O=$(git describe maint)
+git shortlog --no-merges $O..maint

RelNotes

-Documentation/RelNotes-1.6.6.txt
\ No newline at end of file
+Documentation/RelNotes-1.6.6.1.txt
\ No newline at end of file