disable lang_links if add_lang_links=False

Thank you for your great plugin!

I suggest to add add_lang_links config option. This option is True by default, and when set to False , you can remove language links on top of the pages.

@@ -31,6 +31,7 @@ plugins:
           section title: "Sección"
           subsection: "Subsección"
           page title: "Página con título traducido"
+      add_lang_links: False

before	after

And, add site_url to mkdocs.yml.

The site_url configuration option is now required. If it is not set, a warning will be issued. In a future release an error will be raised (#2189).

https://www.mkdocs.org/about/release-notes/#backward-incompatible-changes-in-12