Add missing navigation for github_organization_role_team_assignment (#2787)

Author: nickfloyd

website/github.erb

@@ -286,6 +286,9 @@
             <li>
               <a href="/docs/providers/github/r/organization_custom_properties.html">github_organization_custom_properties</a>
             </li>
+            <li>
+              <a href="/docs/providers/github/r/organization_role_team_assignment.html">github_organization_role_team_assignment</a>
+            </li>
             <li>
               <a href="/docs/providers/github/r/organization_project.html">github_organization_project</a>
             </li>