From Facebook Developer Wiki

Description

For apps that can be added to Facebook Pages, this adds a standardized edit header for canvas pages so that the Page owner can easily jump to their Page's app configuration.

Notes

• This tag should be placed at the top of all pages that the Page admin can use to edit their application on their page.
• This tag only works on a canvas page.
• This tag should only be displayed to an admin of a Facebook Page that has your application added.