Update cli docs with metadata command

Author: dbanck

website/docs/cli/commands/index.mdx

@@ -43,6 +43,7 @@ All other commands:
   import        Associate existing infrastructure with a Terraform resource
   login         Obtain and save credentials for a remote host
   logout        Remove locally-stored credentials for a remote host
+  metadata      Metadata related commands
   output        Show output values from your root module
   providers     Show the providers required for this configuration
   refresh       Update the state to match remote systems