little endian: present byte order, using std to_le_bytes

[Horki]

Hi @encody little-endian in rust idiomatic way

Using to_le_bytes https://godbolt.org/z/bxaTes

Previous https://godbolt.org/z/jve699

[encody]

@alex-sobolev I'm just leaving this open so people can see it, but I won't merge because I would like to keep the code the same as what is in the videos.