Fix QLDoc for ResultVariableDecl

Author: owen-mc

go/ql/lib/semmle/go/Decls.qll

@@ -649,17 +649,23 @@ class ReceiverDecl extends FieldBase, Documentable, ExprParent {
  * Examples:
  *
  * ```go
+ * int
+ * string
  * error
  * r io.Reader
+ * output string
+ * err error
  * x, y int
  * ```
  *
  * as in the following code:
  *
  * ```go
- * func f(error) { return nil }
- * func g(r io.Reader) { return nil }
- * func h(x, y int) { return }
+ * func f1() int { return 0 }
+ * func f2(input string) (string, error) { return "", nil }
+ * func f3(a int) (r io.Reader) { return nil }
+ * func f4(input string) (output string, err error) { return}
+ * func f5(e error) (x, y int) { return }
  * ```
  */
 class ResultVariableDecl extends ParameterOrResultDecl {