Adds help for update

bin/update

@@ -309,7 +309,27 @@ update-postpone() {
 }
 
 _print_help() {
+    echo -e "\033[32mupdate\033[0m"
+    echo -e "Thomas Forgione <thomas@forgione.fr>"
+    echo -e "A script that automatically updates your system"
     echo
+   _print_usage
+}
+
+_print_usage() {
+    echo -e "\033[33mUSAGE:\033[0m"
+    echo -e "    update <subcommand>"
+    echo
+    echo -e "\033[33mSUBCOMMANDS:\033[0m"
+    echo -e "    \033[32msystem\033[0m          Updates the system (Debian, Archlinux, Fedora)"
+    echo -e "    \033[32mrust\033[0m            Updates rust and rust packages (requires rustup)"
+    echo -e "    \033[32mnpm\033[0m             Updates npm packages (in ~/.config/npmbin)"
+    echo -e "    \033[32mdotfiles\033[0m        Updates the dotfiles"
+    echo -e "    \033[32mneovim\033[0m          Updates the neovim packages"
+    echo -e "    \033[32mcheck\033[0m           Checks whether the system has been recently updated"
+    echo -e "    \033[32mstartup\033[0m         Same as \`update check\` but is silent in case of success"
+    echo -e "    \033[32mpostpone\033[0m        Skip the current update (disable check warnings)"
+    echo -e "    \033[32mforce-unlock\033[0m    Deletes the lock file"
 }
 
 partial-test() {
@@ -407,11 +427,19 @@ main() {
         local lock_required=1
 
         for part in $@; do
+
+            if [ $part == "-h" ] || [ $part == "--help" ]; then
+                _print_help
+                exit 0
+            fi
+
             partial-test $part
             if [ $? -ne 0 ]; then
                 echo -e "\033[1;31merror:\033[0m unrocognized update command \"$part\""
+                _print_usage
                 return 1
             fi
+
             partial-requires-lock $part
             lock_required=$(($lock_required * $?))
         done