CPP implementation: does not reference a required separator character

The C++ implementation states:

> // Returns an Open Location Code with code_length significant digits. The string
> // returned may be one character longer if it includes a separator character
> // for formatting.

This is underspecified. Every plus code will have a separator character. CITATION NEEDED. Therefore a better wording would be to say:

> // Returns an Open Location Code with code_length significant digits. The string
> // returned will be one character longer because it includes a separator character
> // for formatting.