changes to mrb_load_string() version

Hello-World.md

@@ -4,24 +4,15 @@
 
 /* Include the mruby header */
 #include <mruby.h>
-#include <mruby/proc.h>
-#include <mruby/data.h>
 #include <mruby/compile.h>
 
 int main(void)
 {
-  struct mrb_parser_state *p;
   mrb_state *mrb = mrb_open();
   char code[] = "p 'hello world!'";
   printf("Executing Ruby code from C!\n");
 
-  p = mrb_parse_string(mrb, code, NULL);
-  int n;
-  n = mrb_generate_code(mrb, p->tree);
-  mrb_run(mrb, mrb_proc_new(mrb, mrb->irep[n]), mrb_top_self(mrb));
-  if (mrb->exc) {
-    mrb_p(mrb, mrb_obj_value(mrb->exc));
-  }
+  mrb_load_string(mrb, code);
   return 0;
 }
 ```
@@ -29,7 +20,7 @@ compile & link
 ```
 $ gcc -Iinclude hello.c lib/libmruby.a -lm -o hello.out
 ```
-execute
+execution
 ```
 $ ./hello.out
 Executing Ruby code from C!