website/docs: Fix websocket default config for nginx proxy manager (#11621)

* Comment out problematic config at _nginx_proxy_manager.md

Resolves:
- https://github.com/goauthentik/authentik/issues/10010
- https://github.com/goauthentik/authentik/discussions/7323
- https://github.com/goauthentik/authentik/issues/11453
- https://www.reddit.com/r/Authentik/comments/1c5sf6l/authentik_with_nginx_proxy_manager_not_possible/

Signed-off-by: Mahmoud AlyuDeen <mahmoudalyudeen@gmail.com>

* Add working websocket configuration for nginx-proxy-manager.

Signed-off-by: Mahmoud AlyuDeen <mahmoudalyudeen@gmail.com>

* remove commented out settings

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

---------

Signed-off-by: Mahmoud AlyuDeen <mahmoudalyudeen@gmail.com>
Signed-off-by: Jens Langhammer <jens@goauthentik.io>
Co-authored-by: Jens Langhammer <jens@goauthentik.io>

website/docs/add-secure-apps/providers/proxy/_nginx_proxy_manager.md

@@ -1,10 +1,4 @@
 ```
-# Upgrade WebSocket if requested, otherwise use keepalive
-map $http_upgrade $connection_upgrade_keepalive {
-    default upgrade;
-    ''      '';
-}
-
 # Increase buffer size for large headers
 # This is needed only if you get 'upstream sent too big header while reading response
 # header from upstream' error when trying to access an application protected by goauthentik
@@ -20,9 +14,6 @@ location / {
     # Set any other headers your application might need
     # proxy_set_header Host $host;
     # proxy_set_header ...
-    # Support for websocket
-    proxy_set_header Upgrade $http_upgrade;
-    proxy_set_header Connection $connection_upgrade_keepalive;
 
     ##############################
     # authentik-specific config