Merge pull request PrefectHQ#1590 from frsann/azureml-tasks

Implement Azure ML Service tasks

Merge pull request PrefectHQ#1537 from PrefectHQ/serialize-all-envs

Serialize all environments

Merge pull request PrefectHQ#1481 from PrefectHQ/context-config

Embedding config into context

Merge pull request PrefectHQ#1435 from PrefectHQ/org-062

Archive 0.6.2 documentation

Merge pull request PrefectHQ#1434 from PrefectHQ/new-exec

New executor

Merge pull request PrefectHQ#1333 from PrefectHQ/slack_readme

Add new unlimited slack invite link to README

Merge pull request PrefectHQ#1242 from PrefectHQ/lets-0.6.0

Lets 0.6.0

Update marshmallow dependency based on new release of marshmallow

Merge pull request PrefectHQ#1089 from PrefectHQ/cut-054

Archive docs and update changelog in preparation for release

Merge pull request PrefectHQ#1007 from PrefectHQ/storage-update

Add fix for calling serialize twice