Add cinder database connection parameters

[database]
idle_timeout
max_pool_size
max_retries
max_overflow

Change-Id: I6fac03a5616678ae99a1ed95fd40e34b47685ae8
Related-prod: PROD-26294
diff --git a/README.rst b/README.rst
index 824019f..a3a507c 100644
--- a/README.rst
+++ b/README.rst
@@ -844,6 +844,7 @@
             secret_key: secret
 
 Cinder service supports to define iscsi_helper for lvm backend.
+=======
 
 .. code-block:: yaml
 
@@ -870,6 +871,30 @@
       controller:
         ...
         scheduler_default_filters: (filters)
+=======
+
+* Cinder database connection setup:
+
+.. code-block:: yaml
+
+    cinder:
+      controller:
+        enabled: True
+        ...
+        database:
+          idle_timeout: 280
+          max_pool_size: 30
+          max_retries: '-1'
+          max_overflow: 40
+      volume:
+        enabled: True
+        ...
+        database:
+          idle_timeout: 280
+          max_pool_size: 30
+          max_retries: '-1'
+          max_overflow: 40
+
 
 Upgrades
 ========