Off-by-one error in documentation for reduce32

[SWilson4]

The documentation for reduce32 states that the output is in the range [-6283009, 6283007]. The range is actually [-6283009, 6283008], as evaluating reduce32 at 2^{31} - 2^{22} - 1 will illustrate.

I have a branch which fixes both this issue and #55 since they're quite minor.

[sduyyy]

@SWilson4 how we evaluate reduce32 at 2^{31} - 2^{22} - 1 ,will you please give a detail description?