PocketStoriesChange was called only once - to clean the shown stories when the
user gets to the homescreen and the Pocket feature is disabled - useful for the
situations in which the user returns after disabling the feature in settings.
Populating the store with recommended stories to show was already happening
based on 'PocketStoriesCategoriesChange' and sponsored stories will be added by
using 'PocketSponsoredStoriesChange' so renaming 'PocketStoriesChange' will
help on reducing any confusion in the future.
Also added documentation for all Pocket related actions from AppStore and
removed the 'UndocumentedPublicClass' detekt suppressions.
