Allow to enable admin api

This patch adds ability to enable admin api from pillar.

Change-Id: I9feee7b8081f23fcb89bf6e91543e09c2542cbe3
Related-Prod: https://mirantis.jira.com/browse/PROD-15865
diff --git a/README.rst b/README.rst
index 943fbea..c07a44d 100644
--- a/README.rst
+++ b/README.rst
@@ -24,6 +24,9 @@
             rndc_algorithm: hmac-sha512
         api:
           base_uri: 'http://127.0.0.1:9001'
+        admin_api:
+          enabled: true
+          enabled_extensions_admin: quotas
         bind:
           api:
             address: 127.0.0.1