Bug in Word Segmentation demo

[Lucretiel]

Consider the string "abc를".

According to the word segmentation rules, this should be treated as a single word (see detailed discussion: unicode-rs/unicode-segmentation#90, rust-lang/regex#743). However, the current demo site splits it into two words. While splitting here is permitted per the Notes section on splitting between different character sets, the formal rules are that there should be no split here, which is what the demo site should reflect.