Update testing.md

Fixed Parameter Generator table

docs/reference/testing.md

@@ -110,6 +110,7 @@ namespace:
 | `Bool()`                     | Yields sequence `{false, true}`.            |
 | `Combine(g1, g2, ..., gN)`   | Yields as `std::tuple` *n*-tuples all combinations (Cartesian product) of the values generated by the given *n* generators `g1`, `g2`, ..., `gN`. |
 | `ConvertGenerator<T>(g)`     | Yields values generated by generator `g`, `static_cast` to `T`. |
+
 The optional last argument *`name_generator`* is a function or functor that
 generates custom test name suffixes based on the test parameters. The function
 must accept an argument of type