chore(nginx): add reverse proxy snippet, to check

snippets/nginx/reverse proxy with host header override.conf

@@ -0,0 +1,20 @@
+server {
+    listen 443 ssl;
+    server_name code.example.org;
+
+    ssl_certificate     /etc/nginx/ssl/code.example.org.crt;
+    ssl_certificate_key /etc/nginx/ssl/code.example.org.key;
+
+    ssl_protocols       TLSv1.2 TLSv1.3;
+    ssl_ciphers         HIGH:!aNULL:!MD5;
+
+    location / {
+        proxy_pass https://gitea.example.org:443;
+        proxy_set_header Host gitea.example.org;
+
+        # Optional but recommended
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Forwarded-Proto https;
+    }
+}