[Datadog] Add note about valid log levels for agent 6 (#3598)

* add note about valid log levels for agent 6

* extra comment line to match style

* version bump

* remove trailing space

stable/datadog/Chart.yaml

@@ -1,5 +1,5 @@
 name: datadog
-version: 0.10.6
+version: 0.10.7
 description: DataDog Agent
 keywords:
 - monitoring

stable/datadog/values.yaml

@@ -65,6 +65,8 @@ datadog:
 
   ## Set logging verbosity.
   ## ref: https://github.com/DataDog/docker-dd-agent#environment-variables
+  ## Note: For Agent6 (image `datadog/agent`) the valid log levels are
+  ## trace, debug, info, warn, error, critical, and off
   ##
   logLevel: WARNING