The reason why we moved the menu to the outliner is that we prefer to have all similar functionality at one place if even possible. And not cluttered across several menus and editors like in Blender. And the outliner is the place to deal with objects and collections. So this move was just logical.
The manual is still work in progress, and may need serveral more months until it is finished. But this menu should be mentioned in the current available parts of the manual already. I’ll have a look.
Beware of a possible hotkey conflict with hotkey M. This is our hotkey to mark a seam in edit mode.