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 want web developers to write more declarative code, not less. This calls for eliminating the standards bottleneck to introducing new declarative forms, and giving library and framework authors the tools to create them."

"writing a declarative code" calls for "eliminate bottleneck" and "giving tool".
not for "eliminate bottleneck" and "giving tool" for developer for "writing a declarative code" isn't it ?