docs: adding circuit relay tutorial (wip)

Author: dryajov

examples/exchange-files-in-browser/public/app.js

@@ -37,8 +37,14 @@ function start () {
         Addresses: {
           Swarm: [
             // '/dns4/wrtc-star.discovery.libp2p.io/tcp/443/wss/p2p-webrtc-star'
-            '/dns4/ws-star.discovery.libp2p.io/tcp/443/wss/p2p-websocket-star'
+            // '/dns4/ws-star.discovery.libp2p.io/tcp/443/wss/p2p-websocket-star'
           ]
+        },
+        Bootstrap: [],
+        EXPERIMENTAL: {
+          relay: {
+            enabled: true
+          }
         }
       }
     }