en.yml - Remove confusing information from intro

While the triple-entry bookkeeping reference is very interesting, I think it's trying to explain bitcoin with an even more obscure analogy.This paragraph should help the reader relate bitcoin to something they already know. It seems to me that out of a 1000 readers there might be one newcomer to say, after reading this, "oh yeah, now I understand bitcoin better!" and at least 999 will be just more confused.