Small fix in the documentation of ulong_extras
Small fix in the documentation of ulong_extras

fredrik-johansson/flint2,dsroche/flint2,jpflori/flint2,dsroche/flint2,jpflori/flint2,wbhart/flint2,jpflori/flint2,fredrik-johansson/flint2,fredrik-johansson/flint2,dsroche/flint2,jpflori/flint2,dsroche/flint2,wbhart/flint2,wbhart/flint2