In the api-docs package for Atom, the keyboard shortcut ctrl+d doesn’t work. The documentation for api-docs is located at https://atom.io/packages/api-docs and says “Place your cursor on the phrase you want to search for and press ctrl+d to search.” But when I do this, nothing happens.
I just ran into this issue as well. What I discovered is that there is a conflict in keybindings for the emmet and api-docs packages for ctrl-d. After some searching around I found Atom Discuss - Key-binding hell on the Atom Discuss site which got me pointed in the right direction.
You can bring up the Keybindings Resolver (Cmd-. on Mac) to view keybindings, then press the desired keyboard shortcut (ctrl-d in this case) to view all of the keybindings for that shortcut. This showed that emmet was the ‘winning’ keybinding.