fix(docs): Add the missing docs

Because I was too stupid to regen the docs and flake made it so we
didn't get a reminder

docs/helm/helm_package.md

@@ -30,6 +30,7 @@ helm package [flags] [CHART_PATH] [...]
       --keyring string           location of a public keyring (default "~/.gnupg/pubring.gpg")
       --save                     save packaged chart to local chart repository (default true)
       --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)
       --sign                     use a PGP private key to sign this package
   -f, --values valueFiles        specify values in a YAML file or a URL(can specify multiple) (default [])
       --version string           set the version on the chart to this semver version
@@ -49,4 +50,4 @@ helm package [flags] [CHART_PATH] [...]
 ### SEE ALSO
 * [helm](helm.md)	 - The Helm package manager for Kubernetes.
 
-###### Auto generated by spf13/cobra on 14-Mar-2018
+###### Auto generated by spf13/cobra on 6-Apr-2018