Documentation of slicing wires still says Ctrl + right mouse button, this uses Alt key now

[rvangeijtenbeek]

On https://nodered.org/docs/user-guide/editor/workspace/wires the section on slicing wires still says Ctrl + right mouse button, but this was changed to Alt + left mouse button in one of the 3.0 betas. I also noticed the markup for keyboard keys was not consistent. I created a pull request.