Update firstruneprog.en.md

subjects/firstruneprog.en.md

@@ -1,4 +1,15 @@
-## firstrune
+## firstruneprog
+
+##**WARNING! VERY IMPORTANT!**
+
+For this exercise a function will be tested **with the exam own main**. However the student **still needs** to submit a structured program:
+
+This means that:
+
+- The package needs to be named `package main`.
+- The submitted code needs one declared function main(```func main()```) even if empty.
+- The function main declared needs to **also pass** the `Restrictions Checker`(illegal functions tester). It is advised for the student to just empty the function main after its own testings are done.
+- Every other rules are obviously the same than for a `program`.
 
 ### Instructions
 
@@ -14,4 +25,4 @@ func FirstRune(s string) rune {
 
 ### Note
 
-Remember to submit a main function testing the function
+Remember to submit a main function testing the function