[stable] [changelog] Add item for noreturn main

changelog/main_return_type.dd

@@ -0,0 +1,9 @@
+`main` can now return type `noreturn` and supports return inference
+
+If `main` never returns (due to an infinite loop or always throwing an
+exception), it can now be declared as returning `noreturn`.
+See https://dlang.org/spec/type.html#noreturn.
+
+If `main` is declared with `auto`, the inferred return type must be
+one of `void`, `int` and `noreturn`.
+