website/docs: fix missing optional Authorization headers (#10932)

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

website/docs/providers/proxy/_nginx_proxy_manager.md

@@ -44,6 +44,11 @@ location / {
     proxy_set_header X-authentik-email $authentik_email;
     proxy_set_header X-authentik-name $authentik_name;
     proxy_set_header X-authentik-uid $authentik_uid;
+
+    # This section should be uncommented when the "Send HTTP Basic authentication" option
+    # is enabled in the proxy provider
+    # auth_request_set $authentik_auth $upstream_http_authorization;
+    # proxy_set_header Authorization $authentik_auth;
 }
 
 # all requests to /outpost.goauthentik.io must be accessible without authentication