Invalid requirements for insert in the documentation

[vinipsmaker]

Documentation states:

it must also be true that n < length(xs)

So if I have a sequence of size 2, the only valid indexes are 0 and 1 then I wouldn't be able to insert a new element at all valid places. Insert means insert before, so it should be valid to insert before the end iterator (i.e. length(xs)) and the actual requirement should be:

it must also be true that n <= length(xs)

I haven't fully tested, but the compiler accepts n=length(xs), so for now I'm assuming that only the documentation is outdated.

Thank you for the excellent library.