Doc add remove object

Closes #4618.

![addObject](https://api.monosnap.com/image/download?id=88iUUvsvt4mPfPzAB8rwHc6prYRkE2)

![removeObject](https://api.monosnap.com/image/download?id=92i0ZwfXW6VveO1IMQzx64GdhC4Xe6)