Fix wrong var name and typo

Author: Christoph Rumpel

.env.example

@@ -3,5 +3,5 @@ WEBHOOK_VERIFY_TOKEN=
 PAGE_ACCESS_TOKEN=
 
 # Bot platforms
-APIAI_TOKEN=
+DIALOGFLOW_TOKEN=
 WITAI_TOKEN=

index.php

@@ -26,7 +26,7 @@
 
     // Example 3: If you want to use a bot platform like Dialogflow
     // Don't forget to place your Dialogflow Client access token in the .env file
-    // $replyMessage = $chatbotHelper->getAnswer($message, 'dialoglow');
+    // $replyMessage = $chatbotHelper->getAnswer($message, 'dialogflow');
 
     // Example 4: If you want to use a bot platform like wit.ai
     // Don't forget to place your Wit.ai Client access token in the .env file (WITAI_TOKEN)