Menu Customizer: readme updates for version 0.0.6, indicating that it's getting less alpha and that it now supports live-previewing.

git-svn-id: https://plugins.svn.wordpress.org/menu-customizer/trunk@961893 b8457f37-d9ea-0310-8a92-e5e31aec5664
Menu Customizer: version bump.

git-svn-id: https://plugins.svn.wordpress.org/menu-customizer/trunk@961897 b8457f37-d9ea-0310-8a92-e5e31aec5664