Thanks, I was able to add the library, I just couldn't find the documentation. NXP might want to put a link to the documentation on the SDK home page (SDK).
Also, that link you provided to the documentation is Rev 0. Is that the latest? I'm finding errors in the button documentation:
1) button_gpio_config_t has three fields in the documentation, but four in the source
2) BUTTON_HANDLE_DEFINE takes two arguments in the documentation, but one in the source. BUTTON_HANDLE_ARRAY_DEFINE takes two arguments, but isn't documented.
I gotta believe there's a newer rev of the documentation out there, but I can't find it.