samples: Added comments (#748)

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dialogflow/snippets/src/main/dialogflow/Example.java

@@ -18,6 +18,11 @@
 
 // [START dialogflow_webhook]
 
+// TODO: add GSON dependency to Pom file
+// (https://mvnrepository.com/artifact/com.google.code.gson/gson/2.8.5)
+// TODO: Uncomment the line bellow before running cloud function
+// package com.example;
+
 import com.google.cloud.functions.HttpFunction;
 import com.google.cloud.functions.HttpRequest;
 import com.google.cloud.functions.HttpResponse;