Update the link to numeric classes description

[coderbee]

The following link seems to be broken in the README description.

"For an additional, more detailed description of the Numeric classes in dsptools: see The Numbers ReadMe"
https://github.com/ucb-bar/dsptools/blob/master/src/main/scala/dsptools/numbers/README.md

[NignetShark]

If it helps, you can find all the documentation at https://github.com/ucb-bar/dsptools/blob/master/doc/

[coderbee]

Thanks, I'll look at this