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/single-vm.rst b/doc/source/guides/single-vm.rst
index 515cd50..53c3fa9 100644
--- a/doc/source/guides/single-vm.rst
+++ b/doc/source/guides/single-vm.rst
@@ -64,7 +64,7 @@
             cd devstack
             echo '[[local|localrc]]' > local.conf
             echo ADMIN_PASSWORD=password >> local.conf
-            echo MYSQL_PASSWORD=password >> local.conf
+            echo DATABASE_PASSWORD=password >> local.conf
             echo RABBIT_PASSWORD=password >> local.conf
             echo SERVICE_PASSWORD=password >> local.conf
             echo SERVICE_TOKEN=tokentoken >> local.conf