Put comments into example scripts.

scripts/function_decl2.rhai

@@ -1,5 +1,12 @@
+// This script defines a function with two parameters
+
+let a = 3;
+
 fn addme(a, b) {
-    a+b
+    a = 42;             // notice that 'a' is passed by value
+    a + b;              // notice that the last value is returned even if terminated by a semicolon
 }
 
-print(addme(3, 4))
+print(addme(a, 4));     // should print 46
+
+print(a);               // should print 3 - 'a' is never changed