fix: use grep -q instead of pipe dev null

- improve syntax in command not found handler

files/zsh/main.zsh

@@ -2,7 +2,7 @@ export MARKPATH=$HOME/.marks
 alias sedi='sed -i "" -e'
 
 command_not_found_handler () {
-  if [ -f Makefile ] && grep "^$1:" Makefile > /dev/null; then
+  if [ -f Makefile ] && grep -q "^$1:" Makefile; then
     local rule=$(echo $1 | awk -F ":" '{print $1}')
     make $rule
     return 0