Bitmap-Fonts: add fontwriter link

[rotter]

You should definitely add fontwriter to the bitmap-fonts readme. Also possibly/probably integrate it into main libgdx tools. It works very well, much better than running weird programs that never work well such as Hiero (or some that are paid).

https://github.com/libgdx/libgdx.github.io/edit/dev/wiki/graphics/2d/fonts/bitmap-fonts.md

Fontwriter: https://github.com/tommyettinger/fontwriter

[Frosty-J]

Does that require TextraTypist? The wiki generally doesn't cover tools for third-party libraries.