src/tconv.3: fix doc about fromcode and tocode [ci skip]
src/tconv.3: fix doc about fromcode and tocode [ci skip]

jddurand/c-marpaESLIF,jddurand/c-marpaESLIF,jddurand/c-marpaESLIF,jddurand/c-marpaESLIF,jddurand/c-marpaESLIF