Edit: /usr/share/nano/nanohelp.nanorc (390B)
## This is meant for highlighting key combos in a nano help text.
# It should not apply to any normal file, so no fileregex.
syntax nanohelp
# Key combos:
color cyan "\^[]4-8A-Z^\_◀▶▲▼]" "[◀▶▲▼]" "(\^|M-)Space" "\
"
# Quoted indicators:
color brightred "'(\^|M-)'"