Correct the equation for Y' in the comment of point_double function
CLA: trivial
@@ -813,7 +813,7 @@ static void copy_conditional(felem out, const felem in, limb icopy)
* Double an elliptic curve point:
* (X', Y', Z') = 2 * (X, Y, Z), where
* X' = (3 * (X - Z^2) * (X + Z^2))^2 - 8 * X * Y^2
- * Y' = 3 * (X - Z^2) * (X + Z^2) * (4 * X * Y^2 - X') - 8 * Y^2
+ * Y' = 3 * (X - Z^2) * (X + Z^2) * (4 * X * Y^2 - X') - 8 * Y^4
* Z' = (Y + Z)^2 - Y^2 - Z^2 = 2 * Y * Z
* Outputs can equal corresponding inputs, i.e., x_out == x_in is allowed,
* while x_out == y_in is not (maybe this works, but it's not tested).
