Add docstring to the Boa lexer.
Add docstring to the Boa lexer.

dscorbett/pygments,dscorbett/pygments,pygments/pygments,dscorbett/pygments,pygments/pygments,dscorbett/pygments,dscorbett/pygments,pygments/pygments,pygments/pygments,pygments/pygments,dscorbett/pygments,pygments/pygments,pygments/pygments,dscorbett/pygments,pygments/pygments,dscorbett/pygments,dscorbett/pygments,pygments/pygments,pygments/pygments,dscorbett/pygments,dscorbett/pygments,dscorbett/pygments,dscorbett/pygments,pygments/pygments,dscorbett/pygments,pygments/pygments,dscorbett/pygments,pygments/pygments,dscorbett/pygments,dscorbett/pygments,pygments/pygments,pygments/pygments,pygments/pygments,pygments/pygments,dscorbett/pygments,pygments/pygments