[tuple] remove superfluous conversion in example

[ricejasonf]

The documentation states that the result of tuple_c is functionally equivalent to the call to make_tuple so the example should not require a conversion. Correct me if I am wrong.

I've seen confusion about this before, and here is the question that prompted this:
https://stackoverflow.com/questions/50101953/why-is-the-type-of-boosthanatuple-c-implementation-defined

Thanks 😄

[ldionne]

You are right. Not sure why there's a conversion in the first place.