Lean is the concept of developing the easiest solution and doing only what is required and useful. If processes are not adding value, then processes need to change. Lean is a focus on efficiently developing the needed system.
Only document the useful stuff. Know both what is required and who the target audience is for all system and user documentation.
Develop a system anticipating change and code in a way that expects change is coming. Leave options available in anticipating growth of the system and increased usage.