Update README.md

README.md

@@ -47,3 +47,7 @@ Below is all command that use to execute react native project for android and iO
 2. open xCode workspace by execute : `Runner.xcworkspace` <br>
 3. clean app by go to Product > Clean Build Folder...
 4. run app by go to Product > Build -->
+
+## Expected behavior
+- When user's phone is called, alert shows up showing the caller number + who the caller is
+- Doesn't show alert is caller number is already saved in contacts