message: Update 'return' statement syntax in LangRef to reflect the actual parsing syntax.
diff: @@ -1094,7 +1094,7 @@ one can choose to apply MLFunctions when it is beneficial.
  Syntax:
  ``` {.ebnf}
  -return-stmt ::= `return` ssa-use-and-type-list?
  +return-stmt ::= `return` (ssa-use-list `:` type-list-no-parens)?
  ```
  The arity and operand types of the return statement must match the result of the
  