docs(helm): added documentation for HELM_KEY_PASSPHRASE

Added description for HELM_KEY_PASSPHRASE

Signed-off-by: Anumita Shenoy <ansheno@microsoft.com>

cmd/helm/helm.go

@@ -71,6 +71,9 @@ Environment:
   $HELM_TLS_KEY        path to TLS client key file for authenticating to Tiller (default "$HELM_HOME/key.pem")
   $HELM_TLS_VERIFY     enable TLS connection between Helm and Tiller and verify Tiller server certificate (default "false")
   $HELM_TLS_ENABLE     enable TLS connection between Helm and Tiller (default "false")
+  $HELM_KEY_PASSPHRASE set HELM_KEY_PASSPHRASE to the passphrase of your PGP private key. If set, you will not be prompted for
+                       the passphrase while signing helm charts
+
 `
 
 func newRootCmd(args []string) *cobra.Command {

docs/helm/helm.md

@@ -31,6 +31,9 @@ Environment:
   $HELM_TLS_KEY        path to TLS client key file for authenticating to Tiller (default "$HELM_HOME/key.pem")
   $HELM_TLS_VERIFY     enable TLS connection between Helm and Tiller and verify Tiller server certificate (default "false")
   $HELM_TLS_ENABLE     enable TLS connection between Helm and Tiller (default "false")
+  $HELM_KEY_PASSPHRASE set HELM_KEY_PASSPHRASE to the passphrase of your PGP private key. If set, you will not be prompted for
+                       the passphrase while signing helm charts
+
 
 
 ### Options
@@ -75,4 +78,4 @@ Environment:
 * [helm verify](helm_verify.md)	 - verify that a chart at the given path has been signed and is valid
 * [helm version](helm_version.md)	 - print the client/server version information
 
-###### Auto generated by spf13/cobra on 4-Sep-2018
+###### Auto generated by spf13/cobra on 16-Oct-2018

docs/provenance.md

@@ -26,7 +26,9 @@ Prerequisites:
 - Keybase command line tools (optional)
 
 **NOTE:** If your PGP private key has a passphrase, you will be prompted to enter
-that passphrase for any commands that support the `--sign` option.
+that passphrase for any commands that support the `--sign` option. You can set the
+HELM_KEY_PASSPHRASE environment variable to that passphrase in case you don't want 
+to be prompted to enter the passphrase.
 
 **NOTE:** The keyfile format for GnuPG changed in version 2.1. Prior to that release
 it was unnecessary to export keys out of GnuPG, and you could instead point Helm