It blows my mind that SourceTree has no documentation. I would rather pay for the product with documentation, than have to Go Fish!
In all fairness, there are just to many open source projects with the same problem. I am a believer that, like unit-tests, documetation should be an integral part of development and the deliverable product.
Most programmers don't have time to read the source, as some suggest.
Atlassian has developed some great products, and this short rant is pertinent to the OSS industry as a whole. Also, I hope it inspires an effort to create some documentation on SourceTree. Many developers will benefit.