Documentation for `std::column` should state that it counts code points, not bytes or graphemes

[ecstatic-morse]

std::column counts the number of unicode characters that precede its invocation in that same line (then adds one). However, this behavior is not stated explicitly in its documentation. It's not unusual for programming languages or editors to use byte indexes for columns (vim does this for example), so I think it's worth clarifying.

[clarfonthey]

Perhaps there could be a version that does take into account graphemes, since the compiler itself already does this to ensure that errors are pointed to properly in the compiler output?