add description of new OCS endpoint

for recommendations of files and folders

see nextcloud/recommendations#458

Signed-off-by: sualko <klaus@jsxc.org>

Author: sualko

developer_manual/client_apis/OCS/index.rst

@@ -10,3 +10,4 @@ OCS API
    ocs-share-api
    ocs-sharee-api
    ocs-status-api
+   ocs-recommendations-api

developer_manual/client_apis/OCS/ocs-recommendations-api.rst

@@ -0,0 +1,39 @@
+=======================
+OCS Recommendations API
+=======================
+
+The OCS Recommendations API allows you to get a list of recommended files and folders with recent activity.
+
+The base URL for all calls to the share API is: *<nextcloud_base_url>/ocs/v2.php/apps/recommendations/api/v1/*
+
+All calls to OCS endpoints require the ``OCS-APIRequest`` header to be set to ``true``.
+
+.. warning:: This API is **experimental** and can change in the future without further notice!
+
+
+Recommendations - Retrieval
+---------------------------
+
+Fetch user-controlled recommendations
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+* Method: ``GET``
+* Endpoint: ``/recommendations``
+* Response:
+    - Status code:
+        + ``200 OK``
+* Result:
+    - `enabled` (boolean) True if recommendations are enabled for user. False otherwise.
+    - `recommendations` (list, optional) List of recommended files and folders, if the user enabled recommendations.
+
+Fetch user setting and recommendations
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+* Method: ``GET``
+* Endpoint: ``/recommendations/always``
+* Response:
+    - Status code:
+        + ``200 OK``
+* Result:
+    - `enabled` (boolean) True if recommendations are enabled for user. False otherwise.
+    - `recommendations` (list) List of recommended files and folders, independent of the users decision.