ref(cmd/upgrade): update reuse-values flag descrip

helps clarify behavior. See #3655

cmd/helm/upgrade.go

@@ -130,7 +130,7 @@ func newUpgradeCmd(client helm.Interface, out io.Writer) *cobra.Command {
 	f.StringVar(&upgrade.version, "version", "", "specify the exact chart version to use. If this is not specified, the latest version is used")
 	f.Int64Var(&upgrade.timeout, "timeout", 300, "time in seconds to wait for any individual Kubernetes operation (like Jobs for hooks)")
 	f.BoolVar(&upgrade.resetValues, "reset-values", false, "when upgrading, reset the values to the ones built into the chart")
-	f.BoolVar(&upgrade.reuseValues, "reuse-values", false, "when upgrading, reuse the last release's values, and merge in any new values. If '--reset-values' is specified, this is ignored.")
+	f.BoolVar(&upgrade.reuseValues, "reuse-values", false, "when upgrading, reuse the last release's values and merge in any overrides from the command line via --set and -f. If '--reset-values' is specified, this is ignored.")
 	f.BoolVar(&upgrade.wait, "wait", false, "if set, will wait until all Pods, PVCs, Services, and minimum number of Pods of a Deployment are in a ready state before marking the release as successful. It will wait for as long as --timeout")
 	f.StringVar(&upgrade.repoURL, "repo", "", "chart repository url where to locate the requested chart")
 	f.StringVar(&upgrade.username, "username", "", "chart repository username where to locate the requested chart")

docs/helm/helm_upgrade.md

@@ -51,7 +51,7 @@ helm upgrade [RELEASE] [CHART]
       --recreate-pods            performs pods restart for the resource if applicable
       --repo string              chart repository url where to locate the requested chart
       --reset-values             when upgrading, reset the values to the ones built into the chart
-      --reuse-values             when upgrading, reuse the last release's values, and merge in any new values. If '--reset-values' is specified, this is ignored.
+      --reuse-values             when upgrading, reuse the last release's values and merge in any overrides from the command line via --set and -f. If '--reset-values' is specified, this is ignored.
       --set stringArray          set values on the command line (can specify multiple or separate values with commas: key1=val1,key2=val2)
       --set-string stringArray   set STRING values on the command line (can specify multiple or separate values with commas: key1=val1,key2=val2)
       --timeout int              time in seconds to wait for any individual Kubernetes operation (like Jobs for hooks) (default 300)
@@ -81,4 +81,4 @@ helm upgrade [RELEASE] [CHART]
 ### SEE ALSO
 * [helm](helm.md)	 - The Helm package manager for Kubernetes.
 
-###### Auto generated by spf13/cobra on 20-Mar-2018
+###### Auto generated by spf13/cobra on 4-Apr-2018