How do you add pictures from your computer without using a third party website?

I don't know when or why, but recently the "Add files" option was removed. Is there any reason for this? I used this quite often because sometimes I don't feel like going through the hassle of using a third party website. Can someone please tell me how to do this?

Edit: This was explained in another post looking through the boards feedback section. http://boards.na.leagueoflegends.com/en/c/site-feedback/sAqj9fZV-attaching-pictures