Fixed typo in class description.

/**

 * An active voice interaction session, providing a facility for the implementation

 * to interact with the user in the voice interaction layer. The user interface is

 * initially shown by default, and can be created be overriding {@link #onCreateContentView()}

 * initially shown by default, and can be created by overriding {@link #onCreateContentView()}

 * in which the UI can be built.

 *

 * <p>A voice interaction session can be self-contained, ultimately calling {@link #finish}