clarify account names, add docs link



before
![screenshot 2014-10-10 15 10 30](https://cloud.githubusercontent.com/assets/74699/4599873/ed8ac550-50cc-11e4-89aa-83ce58a9070c.png)
![screenshot 2014-10-10 15 10 36](https://cloud.githubusercontent.com/assets/74699/4599870/e859d026-50cc-11e4-80fe-3acd3964d91c.png)

after
![screenshot 2014-10-10 15 11 30](https://cloud.githubusercontent.com/assets/74699/4599866/deec9f82-50cc-11e4-98fc-aab0542d161e.png)
![screenshot 2014-10-10 15 41 04](https://cloud.githubusercontent.com/assets/74699/4599997/94d3c50e-50ce-11e4-8801-147782a3c962.png)
![screenshot 2014-10-10 15 11 35](https://cloud.githubusercontent.com/assets/74699/4599868/e475c4c4-50cc-11e4-9359-77850fdb0f9f.png)


you should probably set this as form `help_text`, so you're not duplicating code in templates.