Update API.md (#448)

Author: Laamy

docs/API.md

@@ -206,16 +206,22 @@ relay.on('connect', player => {
   console.log('New connection', player.connection.address)
 
   // Server is sending a message to the client.
-  player.on('clientbound', ({ name, params }) => {
+  player.on('clientbound', ({ name, params }, des) => {
     if (name === 'disconnect') { // Intercept kick
       params.message = 'Intercepted' // Change kick message to "Intercepted"
     }
   })
   // Client is sending a message to the server
-  player.on('serverbound', ({ name, params }) => {
+  player.on('serverbound', ({ name, params }, des) => {
     if (name === 'text') { // Intercept chat message to server and append time.
       params.message += `, on ${new Date().toLocaleString()}`
     }
+    
+    if (name === 'command_request') { // Intercept command request to server and cancel if its "/test"
+      if (params.command == "/test") {
+        des.canceled = true
+      }
+    }
   })
 })
 ```