Update trigger for webhook templates

Templates/WebHook-Generic/metadata.json

@@ -1,5 +1,5 @@
 {
     "name": "Generic Webhook Nodejs function",
     "language": "JavaScript",
-    "trigger": "HttpTrigger"
+    "trigger": "Webhook-Generic"
 }

Templates/WebHook-GitHub/metadata.json

@@ -1,5 +1,5 @@
 {
     "name": "Github Webhook Nodejs Function",
     "language": "JavaScript",
-    "trigger": "HttpTrigger"
+    "trigger": "Webhook-Github"
 }