Add a data-driven example that is 2-dimensional

[eyal0]

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:

BOOST_DATA_TEST_CASE(fib_test, bdata::make(std::vector<std::pair<int,int>>{}), 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:

BOOST_DATA_TEST_CASE(fib_test,
                     bdata::make(
                         std::vector<std::tuple<int,string,string>>{
                           {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.