Add list of design document drafts

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>
Reviewed-by: René Nussbaumer <rn@google.com>

Makefile.am

@@ -236,6 +236,7 @@ docrst = \
 	doc/design-2.2.rst \
 	doc/design-2.3.rst \
 	doc/design-2.4.rst \
+	doc/design-draft.rst \
 	doc/design-oob.rst \
 	doc/design-query2.rst \
 	doc/cluster-merge.rst \

doc/design-draft.rst

+======================
+Design document drafts
+======================
+
+.. toctree::
+   :maxdepth: 2
+
+.. vim: set textwidth=72 :
+.. Local Variables:
+.. mode: rst
+.. fill-column: 72
+.. End:

doc/index.rst

@@ -20,6 +20,7 @@ Contents:
    design-2.2.rst
    design-2.3.rst
    design-2.4.rst
+   design-draft.rst
    cluster-merge.rst
    locking.rst
    hooks.rst