What license agreement is this available under?

[daj]

Please could you add some information to your README, or add a LICENSE.txt file to show what license this code is available under?

GitHub have some helpful advice here:
https://help.github.com/articles/licensing-a-repository/

The most permissive and simplest option is probably to add This project is licensed under the terms of the MIT license. to your README file.

There are lots of other options too, e.g. the Square folks typically use an Apache 2 license and add it in a LICENSE.txt file.
https://github.com/square/picasso/blob/master/LICENSE.txt

[Fusion]

Dan,

The license text can be found in the wiki: https://github.com/Stericson/RootShell/wiki/Licensing

But you are correct that we could make this more obvious.