Incorrect documentation for `check_point_order_equals_group_order`

[tjade273]

In the documentation for check_point_order_equals_group_order, https://github.com/ZenGo-X/curv/blob/44537a746292be65961e9c38191319c17a3d2977/src/elliptic/curves/traits.rs#L185

should presumably read

/// P ≠ 0 ∧ qP = 0

The implementation appears to be correct, so just a simple doc fix should suffice.

[tjade273]

In addition, https://github.com/ZenGo-X/curv/blob/44537a746292be65961e9c38191319c17a3d2977/src/elliptic/curves/bls12_381/g2.rs#L249

should say G2 instead of G1

[leontiadZen]

Thanks @tjade273 , feel free to open a PR :)