That's a feature not a bug. Gradle has phenomenally good documentation. I wish Google kept that level of documentation up for their plugin, or for any part of Android in general. Large swaths of the Gradle user guide are not applicable to the Android plugin because they are for other language specific plugins. The core of the user guide is only a few chapters long and well worth reading.
I was actually excited when I saw the size of the documentation. I really was, and I read it several times over the year.
And then one day, I realized that the web site that I always get back to in order to fix my build files is Stack Overflow, not gradle.org.
The fact that the documentation is so big is an issue, not a feature, because at this size, it's just too big to navigate, contains extreme amounts of redundancies between sections and basically, is not usable in this form.
You know your tool has a problem when the only way to fix problems is to search Stack Overflow.
The Android specific ones are here:
* http://developer.android.com/tools/building/configuring-grad...
* http://tools.android.com/tech-docs/new-build-system/user-gui...