add japanese translate

Hi all.

I wanna advocate this manifesto and principle of Extensible Web to Japanese web devs.

I think this thought is quite important for web future, so I wanna join this as possible as I can.
in japan, there are lots of powerful web developer, but it seem for me that they don't no about this manifesto well.
at first, I translate this in Japanese. but I don't know how publish it.

so I create this PR for asking you.

if it's works fine for you, I'm appreciate it if you publish this for example at https://ja.extensiblewebmanifesto.org/ 
or if that dosen't works. please let me to publish this at my own domain (https://jxck.io) or on my blog (http://jxck.hatenablog.com).

also, thanks for your every works for web.

thanks, and sorry for my poor english ;p

Jxck
We are talking about declarative code, not just "more code".

How about "私たちは、開発者がより宣言的なコードを書いて欲しいと考えています。そのためには、新しい宣言的な形をとりいれる際の標準化のボトルネックを取り除き、ライブラリとフレームワークの作者に、それを作るためのツールを提供することが必要です。" instead? Well "それを作るため" might be confusing...