Also fix bug in description that resulted in a wrong definition of t. And rename keyagg coefficient from 'mu' to 'a' since we don't use the term "musig coefficient" anymore and a is what is used in the paper.
Also fix bug in description that resulted in a wrong definition of t. And rename keyagg coefficient from 'mu' to 'a' since we don't use the term "musig coefficient" anymore and a is what is used in the paper.