You want to encourage thorough and up to date documentation? Don't allow code to be merged without docs. Review documentation at least as stringently as code.

You want to encourage thorough and up to date documentation? Don't allow code to be merged without docs. Review documentation at least as stringently as code. Insist on clear exposition, good grammar, and accuracy. If you're not willing to pay that price, your docs will only be as good as your programmers' intrinsic motivation to write them. The fact that I have never been able to get buy-in for this proposal would argue that our docs may actually be good enough.