doc(wf): Improve docs for `acc`, `well_founded` (#715)
doc(wf): Improve docs for `acc`, `well_founded` (#715)

This PR better clarifies what `acc` and `well_founded` mean (I found them quite cryptic for the longest time).



leanprover-community/lean,leanprover-community/lean,leanprover-community/lean,leanprover-community/lean,leanprover-community/lean,leanprover-community/lean