This is a simple utility addon for site developers and designers that allows you to enforce a "flat" page hierarchy under a certain section of your site. Set the "Force Single Sublevel" page attribute on a top-level page of your site, and any pages added more than 1 level deep will be automatically moved back up to 1 level deep.
For example, if you set this attribute on an "About Us" page, and click the "Add Page" button from a sub-page beneath "About Us", the new page will be created under the "About Us" page instead of under the sub-page.
This is especially useful for new Concrete5 users (or non-technical end users in general) because many people have a hard time understanding the concept of page hierarchies, and if you don't have a robust drop-down menu system implemented, new pages can appear to get "lost" immediately after navigating away from them!
NOTE ABOUT v1.0.1 - This update only effects new installations of the package -- so if you already have version 1.0 of the addon installed, you do not need to upgrade it (but if you want to upgrade it you can do so and nothing will break or change for you).