Updated the default text that comes with it

The default text that comes with the test is not changed to this so some new users would find it easy to follow along (like me)

README.md

@@ -601,13 +601,13 @@ Open the `test/chat_web/controllers/page_controller_test.exs` file
 and replace the line:
 
 ```elixir
-assert html_response(conn, 200) =~ "Welcome to Phoenix!"
+    assert html_response(conn, 200) =~ "Peace of mind from prototype to production"
 ```
 
 With:
 
 ```elixir
-assert html_response(conn, 200) =~ "Phoenix Chat Example"
+    assert html_response(conn, 200) =~ "Phoenix Chat Example"
 ```
 
 Now if you run the tests again, they will pass: