Update phone number input comments

src/components/FieldPhoneNumberInput/FieldPhoneNumberInput.js

@@ -1,3 +1,9 @@
+/**
+ * A text field with phone number formatting. By default uses formatting
+ * rules defined in the fiFormatter.js file. To change the formatting
+ * provide alternative implementations for the format and parse functions
+ * that are passed to the input field.
+ */
 import React from 'react';
 
 import { TextInputField } from '../../components';