Document server setup for CheerpX (#139)

sites/cheerpx/src/content/docs/11-guides/nginx.md

@@ -0,0 +1,53 @@
+---
+title: Basic server setup
+description: Serve your own project using nginx
+---
+
+CheerpX requires [SharedArrayBuffer](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer), which itself requires the site to be cross-origin isolated. This means that the server must set the appropriate headers.
+
+Here's an example of a basic nginx configuration that allows CheerpX to run.
+
+```nginx
+worker_processes  1;
+error_log   nginx_main_error.log info;
+pid nginx_user.pid;
+daemon off;
+
+events {
+    worker_connections  1024;
+}
+
+http {
+    default_type  application/octet-stream;
+    access_log  nginx_access.log;
+    error_log   nginx_error.log info;
+
+    sendfile        on;
+
+    server {
+        listen       8080;
+        server_name  localhost;
+
+        gzip on;
+        gzip_types application/javascript application/wasm text/plain application/octet-stream;
+
+        charset utf-8;
+
+        location / {
+            root .;
+            index  index.html index.htm;
+            add_header 'Cross-Origin-Opener-Policy' 'same-origin' always;
+            add_header 'Cross-Origin-Embedder-Policy' 'require-corp' always;
+            add_header 'Cross-Origin-Resource-Policy' 'cross-origin' always;
+        }
+    }
+}
+```
+
+This configuration will work over localhost in a development environment. When the application is deployed, it must be served over HTTPS.
+
+Then run nginx using this configuration with the following command line.
+
+```bash
+nginx -c nginx.conf -p .
+```