Add missing underscore

docs/guides/tutorials/phoenix_github_oauth.rst

@@ -10,7 +10,7 @@ Phoenix
 In this tutorial, we'll look at
 how you can create an application with authorization through GitHub using
 `Phoenix <https://phoenixframework.org/>`_ and `the official EdgeDB Elixir
-driver </libraries/elixir>`.
+driver </libraries/elixir>`_.
 
 This tutorial is a simplified version of the `LiveBeats
 <https://github.com/fly-apps/live_beats>`_ application from