userguide: Use anchor for list of commands
userguide: Use anchor for list of commands

Fixes #3464

stapelberg/i3,Airblader/i3-original,stapelberg/i3,i3/i3,Airblader/i3,Airblader/i3,Airblader/i3-original,Airblader/i3-original,stapelberg/i3,i3/i3,stapelberg/i3,i3/i3,Airblader/i3-original,Airblader/i3,Airblader/i3,Airblader/i3-original,i3/i3