WIP: domain listing with Gandi

Rethinking the interface already.

cli/domain/domain.go

@@ -0,0 +1,32 @@
+package domain
+
+import (
+	"github.com/urfave/cli/v2"
+)
+
+// DomainCommand supports managing DNS entries.
+var DomainCommand = &cli.Command{
+	Name:      "domain",
+	Usage:     "Manage domains via 3rd party providers",
+	Aliases:   []string{"d"},
+	ArgsUsage: "<domain>",
+	Description: `
+This command supports managing DNS records via 3rd party providers such as
+Gandi DNS. It supports listing, creating, updating and removing all types of
+DNS records that you might need to manage for managing Co-op Cloud apps.
+
+The following providers are supported:
+
+    Gandi DNS https://www.gandi.net
+
+Any new provider can be integrated, we welcome change sets. See the underlying
+DNS library documentation for more. It supports many existing providers and
+allows to implement new provider support easily.
+
+    https://pkg.go.dev/github.com/libdns/libdns
+
+`,
+	Subcommands: []*cli.Command{
+		DomainListCommand,
+	},
+}