do the funky (add libs example)

lib/constants.h

@@ -0,0 +1 @@
+char* HELLO = "Hello, world!";

src/main.c

@@ -1,6 +1,7 @@
 #include <stdio.h>
+#include "constants.h"
 
 int main(int argc, char* argv[]) {
-	printf("Hello, world!\n");
+	printf("%s\n", HELLO);
 	return 0;
 }