Unhardcode logger log level

This patch unhardcodes log level in loggig.conf template.

Change-Id: I971520c8c98f652af01ff88fbda62c02721f4ba5
Related-Prod: https://mirantis.jira.com/browse/PROD-19921
diff --git a/README.rst b/README.rst
index 2b6483c..a7bab40 100644
--- a/README.rst
+++ b/README.rst
@@ -250,6 +250,25 @@
           ossyslog:
             enabled: true
 
+The log level might be configured per logger by using the
+following pillar structure:
+
+.. code-block:: yaml
+
+  ceilometer:
+    server:
+      logging:
+        loggers:
+          <logger_name>:
+            level: WARNING
+
+  ceilometer:
+    agent:
+      logging:
+        loggers:
+          <logger_name>:
+            level: WARNING
+
 
 More Information
 ================