ref(contrib/coreos): remove fleet.socket from user-data

fleet.socket prevented fleet from connecting to peers on coreos 494.0.0 running on vmware.
Merge pull request #2537 from sirwolfgang/master

ref(contrib/coreos): remove fleet.socket from user-data
docs(*): clarify local cluster settings
Merge pull request #2527 from carmstrong/clarify_installing_deis

docs(installing_deis): clarify local settings for Installing Platform
docs(schedule): add release schedule & planning documentation