Updated configuration and docs for MYSQL_PASSWORD

Updated MYSQL_PASSWORD to DATABASE_PASSWORD in sample
configuration and existing docs

Change-Id: Iafb295a0b7707e08a81e6528620db8543d40f7ae
diff --git a/doc/source/guides/neutron.rst b/doc/source/guides/neutron.rst
index 4248445..9d4f54a 100644
--- a/doc/source/guides/neutron.rst
+++ b/doc/source/guides/neutron.rst
@@ -52,7 +52,7 @@
         RABBIT_HOST=172.18.161.6
         GLANCE_HOSTPORT=172.18.161.6:9292
         ADMIN_PASSWORD=secrete
-        MYSQL_PASSWORD=secrete
+        DATABASE_PASSWORD=secrete
         RABBIT_PASSWORD=secrete
         SERVICE_PASSWORD=secrete
         SERVICE_TOKEN=secrete