make kn default

Author: andrewgsavage

pint/default_en.txt

@@ -238,7 +238,7 @@ reciprocal_centimeter = 1 / cm = cm_1 = kayser
 # Velocity
 [velocity] = [length] / [time]
 [speed] = [velocity]
-knot = nautical_mile / hour = kt = kn = knot_international = international_knot
+knot = nautical_mile / hour = kn = kt = knot_international = international_knot
 mile_per_hour = mile / hour = mph = MPH
 kilometer_per_hour = kilometer / hour = kph = KPH
 kilometer_per_second = kilometer / second = kps