Outdated docs links

[sebs]

In the header of the project on github, documentation for polymer 1.0 is linked.

Please make the following changes:

• Provide all important docs in this repository, do not rely on polymer js docs for that
• Link to the Latest or even Polymer 2 and 3 documentation, not 1.0
• How is that "beta" going ? Since probably most polymer projects use this respos, is there anything new?

Regards Sebs