Updated FAQ (markdown)

FAQ.md

@@ -1 +1,29 @@
-FAQ
+FAQ
+
+## How can I configure my reverse proxy to serve Portainer?
+
+Here is a working configuration for Nginx (tested on 1.11) to serve Portainer at `myhost.mydomain/portainer`:
+
+```nginx
+upstream portainer {
+    server ADDRESS:PORT;
+}
+
+server {
+  listen 80;
+
+  location /portainer/ {
+      proxy_http_version 1.1;
+      proxy_set_header Connection "";
+      proxy_pass http://portainer/;
+  }
+  location /portainer/ws/ {
+      proxy_set_header Upgrade $http_upgrade;
+      proxy_set_header Connection "upgrade";
+      proxy_http_version 1.1;
+      proxy_pass http://portainer/ws/;
+  }
+}
+```
+
+Replace `ADDRESS:PORT` with the Portainer server/container details.