Handle the hardcoded configuration values

This patch allows to customize the hardcoded configuration values,
as well as introduce new configuration options for heat services
by configmap template

Change-Id: I93056ddf64c737abfcc40151105af129f8b2c2d6
Related-Prod: PROD-29040
diff --git a/README.rst b/README.rst
index 32fa6eb..19a6229 100644
--- a/README.rst
+++ b/README.rst
@@ -293,6 +293,28 @@
             enabled: true
             strategy: ENCRYPT
             secret_key: secret
+
+Heat configmap setup:
+---------------
+
+.. code-block:: yaml
+
+  heat:
+    server:
+      configmap:
+        DEFAULT:
+          debug: true
+        database:
+          idle_timeout: 300
+          min_pool_size: 5
+          max_pool_size: 50
+        oslo_messaging_rabbit:
+          pool_max_size: 30
+          pool_max_overflow: 30
+          pool_recycle: 600
+
+.. code-block::
+
 Upgrades
 ========