hook: add reminder to build css before commiting when needed

hooks/pre-commit

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+modifiedless=$(make -n css | grep less)
+if [[ -n "$modifiedless" ]]
+then
+	echo -e "\e[33;1m[error] remember to run 'make css' before commiting\e[0m"
+	exit 1
+fi