Add ability to set debug level

Each contrail service can be configured with its own
level of debug. These services can be configured:

  contrail-collector
  contrail-query-engine
  contrail-topology
  contrail-snmp-collector
  contrail-vrouter-agent
  contrail-device-manager
  contrail-analytics-api
  contrail-alarm-gen
  contrail-dns
  contrail-svc-monitor
  contrail-control
  contrail-api
  contrail-schema

Closes-bug: #PROD-34313

Change-Id: Ic20e7ac45797a82154ef124aebbab052b5b01b5f
diff --git a/README.rst b/README.rst
index 75ac251..04cfb58 100644
--- a/README.rst
+++ b/README.rst
@@ -832,6 +832,40 @@
         override_rpf_default_by: 'disable'
       ...
 
+Configure log level for Contrail services
+-----------------------------------------
+
+For OpenContrail 4.0 and 4.1 formula supports setting level of
+the log level for contrail services. Default value of debug level
+is `SYS_NOTICE`.
+
+.. code-block:: yaml
+
+    opencontrail:
+      ...
+      config:
+        log_level:
+          api: SYS_NOTICE
+          device_manager: SYS_NOTICE
+          schema: SYS_NOTICE
+          svc_monitor: SYS_NOTICE
+      collector:
+        log_level:
+          alarm: SYS_NOTICE
+          analytics_api: SYS_NOTICE
+          collector: SYS_NOTICE
+          query_engine: SYS_NOTICE
+          snmp: SYS_NOTICE
+          topology: SYS_NOTICE
+      compute:
+        log_level:
+          agent: SYS_NOTICE
+      control:
+        log_level:
+          control: SYS_NOTICE
+          dns: SYS_NOTICE
+      ...
+
 Cassandra GC logging
 --------------------