add explanations for the effects of the prompt function and its return value

Author: alexandru-pocovnicu

Sprint-1/4-stretch-explore/chrome.md

@@ -15,4 +15,7 @@ What effect does calling the `alert` function have?
 Now try invoking the function `prompt` with a string input of `"What is your name?"` - store the return value of your call to `prompt` in an variable called `myName`.
 
 What effect does calling the `prompt` function have?
+It generates an input field
+
 What is the return value of `prompt`?
+whatever is introduced int hte input field