Update HOWTOBUILD doc

[seohy02]

Euphony version has been upgraded, so HOWTOBUILD.md needs to be updated.

[seohy02]

It would be good to fill it out referring to #45 discussion !!

[yeonns]

@seoh02h I made discussion related to this issue 😄
I think it would be good to write draft in discussion and make PR after receiving enough feedback.