Don't list gluetun anymore since configuring a proxy is possible now

Author: unixfox

mkdocs.yml

@@ -32,7 +32,6 @@ nav:
     - 'register-user.md'
     - 'reset-password.md'
     - 'known-exception.md'
-    - 'gluetun.md'
   - 'For public instances Owners':
     - 'takedown.md'
     - 'hide-instance-behind-proxy-server.md'