Add a data-driven example that is 2-dimensional

https://github.com/boostorg/test/blob/9d863d07e864ef663e3e8573b55905099b938d3e/doc/examples/dataset_example67.run.cpp#L41

I got confused when I read the docs about data-driven testing because I made a `vector` of `pair` and each element was treated as a single parameter to the macro. But when I needed to add another parameter, I switched to tuple and got a long compiler error that didn't explain my problem well.

For example, this will work:

```c++
BOOST_DATA_TEST_CASE(fib_test, bdata::make(std::vector>{}), sample) {
...
}
```

and each `sample` will be a `pair`. But if you now want to add a third argument, so you switch `pair` to `tuple`. It will now fail because you now need **three** parameters. The `sample` **won't** be a `tuple`. (I suspect that boost is using the `std::tuple` internally when generating test cases.)

Please add an example how tuple can be used to make a static table. For example:

```c++
BOOST_DATA_TEST_CASE(fib_test,
bdata::make(
std::vector>{
{0, "zero", "cero"},
{1, "one", "uno"},
{6, "six", "seis"}}),
number, english, spanish) {
BOOST_CHECK_EQUAL(to_english(number), english);
BOOST_CHECK_EQUAL(to_spanish(number), spanish);
}
```

Something like that to show off how to make a table.