Add Chinese translation for spec v2.0.0-rc.1

I grab the origin v2.0.0-rc.1 translation from https://github.com/kainy/semver, and follow this issue mojombo/semver#58
Hope this pull request can be merged, although it is still v2.0.0-rc.1 
I will add translation for v2.0.0 when I have spare time.
Thanks. :four_leaf_clover: