1. A computing device comprising: a processing unit; memory; and one or more microphones; the computing device configured with a voice-controlled digital personal assistant to perform operations for discovering capabilities of third-party voice-enabled resources, the operations comprising: receiving, via the one or more microphones, a digital voice input generated by a user; performing natural language processing using the digital voice input to determine a user voice request, wherein the user voice request is a request for available third-party voice-enabled resources installed on the computing device that are capable of performing a task; identifying one or more third-party voice-enabled resources that are capable of performing the task using voice input, wherein the one or more third-party voice-enabled resources are identified using a data structure that defines tasks supported by available third-party voice-enabled resources using voice input, wherein the data structure comprises: information identifying voice commands supported by the available third-party voice-enabled resources; information identifying voice command variations supported by the available third-party voice-enabled resources that define variations of user voice input that will perform the voice command, wherein at least one of the voice commands supports a plurality of different voice command variations; and information identifying voice command examples supported by the available third-party voice-enabled resources, wherein the one or more voice command examples are specific examples of user voice input that, if spoken by the user, will activate the voice command, wherein at least one of the voice commands has a plurality of different voice command examples that activate the voice command; providing a response to the user identifying the one or more third-party voice-enabled resources that are capable of performing the task; receiving a user-initiated command, wherein the user-initiated command identifies a specific third-party voice-enabled application from the one or more third-party voice-enabled resources, wherein the user-initiated command instructs the voice-controlled digital personal assistant to delete a voice command of the specific third-party voice-enabled application from the data structure, and to delete all of the voice command's corresponding voice command variations from the data structure that are associated with the voice command in the data structure, wherein the deleted voice command, and corresponding voice command variations, cannot be performed by user voice input; and performing the user-initiated command to delete the voice command of the specific third-party voice-enabled application from the data structure, and to delete all of the voice command's corresponding voice command variations from the data structure that are associated with the voice command in the data structure.
6. The computing device of claim 1 the operations further comprising: receiving a user-initiated command, wherein the user-initiated command identifies a specific third-party voice-enabled resource from the one or more third-party voice-enabled resources and a request to practice a specific voice command variation for performing a specific task supported by the specific third-party voice-enabled resource.