update README.md

lay the groundwork v.3(firebase#450)

Author: dkuspawono

README.md

@@ -13,7 +13,7 @@ Here are some resources to get help:
 - Start with the quickstart: https://firebase.google.com/docs/functions/write-firebase-functions
 - Go through the guide: https://firebase.google.com/docs/functions/
 - Read the full API reference: https://firebase.google.com/docs/reference/functions/
-- Browse some examples: https://github.com/firebase/functions-samples
+- Browse some examples: https://github.io/firebase/functions-samples
 
 If the official documentation doesn't help, try asking through our official support channels: https://firebase.google.com/support/