Makefile added with Version 1.3

Makefile

@@ -1,4 +1,4 @@
-# Version 1.2 (2025-08-05)
+# git helper Makefile: Version 1.3 (2025-08-05)
 default: help
 
 .ONESHELL:
@@ -34,6 +34,9 @@ init: print_head
 		$(INIT_FILE)
 	fi
 
+update_submodules:
+	git submodule foreach "git checkout master && git pull && git submodule init && git submodule update"
+
 status: print_head
 	giti
 	echo "Submodules:"