Edit documentation.

doc/src/language/return.md

@@ -3,8 +3,14 @@ Return Values
 
 {{#include ../links.md}}
 
+The `return` statement is used to immediately stop evaluation and exist the current context
+(typically a function call) yielding a _return value_.
+
 ```rust
 return;             // equivalent to return ();
 
 return 123 + 456;   // returns 579
 ```
+
+A `return` statement at _global_ level stop the entire script evaluation,
+the return value is taken as the result of the script evaluation.