Mention the '--expires' flag available to the 'tuf gen-key' command
Signed-off-by: Vladimir Diaz <vladimir.v.diaz@gmail.com>
diff --git a/README.md b/README.md
index 7f52b06..977c01f 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@
snapshots should be generated, the repository will be implicitly
initialized to do so when generating keys.
-#### `tuf gen-key <role>`
+#### `tuf gen-key [--expires=<days>] <role>`
Prompts the user for an encryption passphrase (unless the
`--insecure-plaintext` flag is set), then generates a new signing key and
