Bump dcos-docs
Bump dcos-docs

Bump dcos/dcos-docs
  Joel Hamill:
     Fix broken image
     clarified ZK storage for upgrade
     corrected link
  Harpreet Singh Gulati:
     Update the path for new proxy config file

dcos/dcos-website,dcos/dcos-website,dcos/dcos-website,dcos/dcos-website