Add possibility to use MySQL backend

Just for the information:
The base code for row_present state was mainly taken from sqlite3
SaltStack state.

MySQL database schema was taken from:
https://doc.powerdns.com/authoritative/backends/generic-mysql.html

Related-PROD: PROD-21596 (PROD:21596)

Change-Id: If58216b058c352c692ea4997019193dba287038a
diff --git a/README.rst b/README.rst
index f16ed70..8563d18 100644
--- a/README.rst
+++ b/README.rst
@@ -1,63 +1,102 @@
+=====
+Usage
+=====
 
-========
-PowerDNS
-========
+PowerDNS, founded in the late 1990s, is a premier supplier
+of open source DNS software, services and support. Deployed
+throughout the world with some of the most demanding users
+of DNS, we pride ourselves on providing quality software
+and the very best support available.
 
-Sample pillar:
+Sample Pillars
+==============
 
 PowerDNS server with MySQL backend
 
 .. code-block:: yaml
-  powedns:
-    server:
-      enabled: true
-      backend:
-        engine: mysql
-        host: localhost
-        port: 3306
-        name: pdns
-        user: pdns
-        password: password
-      bind:
-        address: 0.0.0.0
-        port: 53
-      axfr_ips:
-        - 10.11.0.0/16
-        - 127.0.0.1
-      api:
-        enabled: true
-        key: SecurePass
-      webserver:
-        enabled: true
-        password: SuperSecurePass
-        address: 0.0.0.0
-        port: 8081
 
+    powerdns:
+      server:
+        api:
+          enabled: True
+          key: VxK9cMlFL5Ae
+        axfr_ips:
+          - 172.16.10.103
+          - 172.16.10.104
+          - 172.16.10.102
+          - 127.0.0.1
+        backend:
+          engine : mysql
+          host : localhost
+          port : 3306
+          dbname : powerdns
+          user : powerdns
+          password : powerdns
+          timeout': 10
+          dnssec : on
+        bind:
+          address: 172.16.10.103
+        overwrite_supermasters: True
+        supermasters:
+          - account: master
+            ip: 172.16.10.103
+            nameserver: ns1.example.org
+          - account: master
+            ip: 172.16.10.104
+            nameserver: ns2.example.org
+          - account: master
+            ip: 172.16.10.102
+            nameserver: ns3.example.org
+        webserver:
+          address: 172.16.10.103
+          enabled: True
+          password: gJ6n3gVaYP8eS
+          port: 8081
 
-PowerDNS server with sqlite backend
+.. note:: If you use one MySQL database across several
+   PowerDNS instances, be sure to pass *-b1* parameter
+   to *salt* command to avoid race condition.
+
+PowerDNS server with SQLite backend
 
 .. code-block:: yaml
-  powerdns:
-    server:
-      enabled: true
-      backend:
-        engine: sqlite
-        dbname: pdns.sqlite
-        dbpath: /var/lib/powerdns
-      bind:
-        address: 127.0.0.1
-        port: 55
-      default-soa-name: ns1.domain.tld
-      soa-minimum-ttl: 3600
-      api:
-        enabled: true
-        key: SecurePass
-      webserver:
-        enabled: true
-        password: SuperSecurePass
-        address: 0.0.0.0
-        port: 8081
+
+    powerdns:
+      server:
+        api:
+          enabled: True
+          key: VxK9cMlFL5Ae
+        axfr_ips:
+          - 172.16.10.103
+          - 172.16.10.104
+          - 172.16.10.102
+          - 127.0.0.1
+        backend:
+          engine: sqlite
+          dbname: pdns.sqlite
+          dbpath: /var/lib/powerdns
+        bind:
+          address: 172.16.10.103
+        overwrite_supermasters: True
+        supermasters:
+          - account: master
+            ip: 172.16.10.103
+            nameserver: ns1.example.org
+          - account: master
+            ip: 172.16.10.104
+            nameserver: ns2.example.org
+          - account: master
+            ip: 172.16.10.102
+            nameserver: ns3.example.org
+        webserver:
+          address: 172.16.10.103
+          enabled: True
+          password: gJ6n3gVaYP8eS
+          port: 8081
 
 
-Read more
-=========
+Documentation
+=============
+
+* https://doc.powerdns.com/
+