addValidatedDonorNumber method
Add a validated donor number to a particular user account. This stores their validated donor number within their account details
Implementation
Future<dynamic> addValidatedDonorNumber(String email, String donorNumber){
String subbedEmail = email.replaceAll('.', ',');
DatabaseReference dbUserRef = FirebaseDatabase.instance.reference().child(
'Users/Nonstaff/$subbedEmail');
return dbUserRef.update({'donorNumber': donorNumber});
}