docs(managing_deis): flesh out platform monitoring docs
Merge pull request #2441 from carmstrong/monitoring_docs

docs(managing_deis): flesh out platform monitoring docs
docs(installing_deis): add quick start guide

This guide adds some quick links to some common tasks that are shared
across multiple cloud provider documentation such as generating a new
SSH key, generating a Discovery URL, configuring DNS and installing
deisctl.
fix(docs): fixup markdown