set Host in the nginx proxy doc examples

docs/docs/configuration/advanced/system.md

@@ -360,6 +360,7 @@ For example, in Nginx:
 
 ```
 location /frigate {
+    proxy_set_header Host $host;
     proxy_set_header X-Ingress-Path /frigate;
     proxy_pass http://frigate_backend;
 }

docs/docs/guides/reverse_proxy.md

@@ -163,6 +163,7 @@ The settings below enabled connection upgrade, sets up logging (optional) and pr
   error_log /data/logs/proxy-host-40_error.log warn;
 
   location / {
+    proxy_set_header Host $host;
     proxy_set_header Upgrade $http_upgrade;
     proxy_set_header Connection $http_connection;
     proxy_http_version 1.1;