Get app data for the page

If the page is for an app like a blog or store then information about the app page is set.

If the page is an app category page, then the full category information will be held in {{ _page.app.category }}.

{{ _page.app.urls }} holds an array of available app URLs.

If the page is for an app item like a blog post, gallery item or store product then that app item information will be held in {{ _page.app.item }}.

{{ _page.app.pageType }} holds the app page type for all apps except for the Pages app.

If the page is an app tag page then the full tag information will be held in {{ _page.app.tag }}.

The following information is set for all app pages, including the Pages app.

{{ _page.app.instanceKey }} holds the app instance key. 

{{ _page.app.instanceName }} holds the name of the app instance.

{{ _page.app.name }} Holds the name of the app. It will be all in lower case. For example, if the app is a blog then for all blog instances {{ _page.app.name }} will hold 'blog'.