Add links to http://ksonnet.heptio.com/

[jhermann]

Link your org's and project's "Website" settings to http://ksonnet.heptio.com/ to make things more discoverable.

[anguslees]

.. except ksonnet.heptio.com is (a) a heptio-specific site, and (b) doesn't mention kubecfg.

Assigning to @hausdorff to sort out the heptio side of things, and what we want to do with ksonnet websites generally (eg ksonnet-lib also doesn't mention kubecfg, and I removed ksonnet-lib from kubecfg's examples some time ago because ksonnet-lib didn't work at the time).

[jessicayuen]

This issue was moved to ksonnet/ksonnet#20