api-ref: move to a v1.1 sub-folder

Make space for v2.
It should not break too much existing links, only the links to
local anchors (like #clusters, #jobs, etc) will be broken,
because it is not possible to redirect server-side based on an
URL fragment like that.
Luckily the generated content ends all in the same HTML page,
so the old links will end up in the new top-level index
which points to the index for v1.1 API documentation (and later
for v2). Not too bad.

Change-Id: I9a75e6567798b8d6d3deed8fc66e362ad2d86b5a

api-ref/source/index.rst

@@ -1,20 +1,12 @@
-:tocdepth: 2
+===================
+Data Processing API
+===================
 
-====================
- Data Processing API
-====================
+Contents:
 
-.. rest_expand_all::
+API content can be searched using the :ref:`search`.
 
-.. include:: cluster-templates.inc
-.. include:: clusters.inc
-.. include:: data-sources.inc
-.. include:: event-log.inc
-.. include:: image-registry.inc
-.. include:: job-binaries.inc
-.. include:: job-executions.inc
-.. include:: job-types.inc
-.. include:: job-binary-internals.inc
-.. include:: jobs.inc
-.. include:: node-group-templates.inc
-.. include:: plugins.inc
+.. toctree::
+    :maxdepth: 2
+
+    v1.1/index

api-ref/source/v1.1/index.rst

@@ -0,0 +1,20 @@
+:tocdepth: 2
+
+========================
+Data Processing API v1.1
+========================
+
+.. rest_expand_all::
+
+.. include:: cluster-templates.inc
+.. include:: clusters.inc
+.. include:: data-sources.inc
+.. include:: event-log.inc
+.. include:: image-registry.inc
+.. include:: job-binaries.inc
+.. include:: job-executions.inc
+.. include:: job-types.inc
+.. include:: job-binary-internals.inc
+.. include:: jobs.inc
+.. include:: node-group-templates.inc
+.. include:: plugins.inc