updated readme

README.md

@@ -50,7 +50,7 @@ Find and save the institution_id of your bank.
 ```
 
 ### 3. Create Auth Link and authenticate with your bank
-Provide a unique reference (e.g. `'mycheckingaccount'`)  per bank account to identify the grant later on.
+Provide a unique reference (e.g. `'mycheckingaccount'`)  per bank connection to identify the grant later on.
 ```py
 ynab_api_import.create_auth_link(institution_id='<institution_id', reference='<reference>')
 ```
@@ -63,6 +63,16 @@ ynab_api_import.import_transactions(reference='<reference>',
                                     budget_id='<budget_id>', 
                                     account_id='<account_id')
 ```
+## Handling of multiple or no active accounts in your bank connection
+The library assumes that you have one active account in your bank connection. It will raise an error if there are
+no active accounts in your connection or more than one. In the latter case you need to provide the correct `resource_id`
+in your call. You can find the `resource_id` by looking into the available options in the error message.
+```py
+ynab_api_import.import_transactions(resource_id='<resource_id>',
+                                    reference='<reference>', 
+                                    budget_id='<budget_id>', 
+                                    account_id='<account_id')
+```
 ## Development
 
 Read the [CONTRIBUTING.md](CONTRIBUTING.md) file.