OnShape link points to wrong version

[tomaski]

readme.md links to version 1.1.0
should be 1.2.1 https://cad.onshape.com/documents/d1cf51356ca66e6a45738c30/v/f17725bc7d9da347304bc9e4/e/61f36bd0b771bfe27606c238

[naorunaoru]

I'll bump this one.

Readme points to 1.2.1 but it should be 2.0.1.