Add English translation for Lili58 build guide

[juanlufont]

This PR adds an English translation of the Lily58 build guide (originally in Japanese).

I have used Google translator for the initial bulk translation from Japanese to English (I do not speak Japanese). Then I have manually corrected the whole text, complementing it with my own experience building a Lily58.

I am not an native English speaker, so the guide may contain some (hopefully minor) grammar mistakes.