Korean text field update

* all punctuation is optional.
* type in Hangeul or lowercase Roman.
* type Roman according to Hangeul spelling.
* accepts alternate spellings: l=r, g=k, b=p, d=t, etc.
* don't type sound changes: type -pn- and not -mn-, type -ssn- and not -nn-.
* practice sound changes on recording page with pronunciation guide.
* report any issues to staff for next-day update.