print usage when missing subcommand

lib/3scale_toolbox/commands/3scale_command.rb

@@ -6,6 +6,7 @@ module ThreeScaleToolbox
   module Commands
     module ThreeScaleCommand
       include ThreeScaleToolbox::Command
+
       def self.command
         Cri::Command.define do
           name        '3scale'
@@ -23,6 +24,10 @@ def self.command
             puts cmd.help
             exit 0
           end
+
+          run do |_opts, _args, cmd|
+            puts cmd.help
+          end
         end
       end
     end

lib/3scale_toolbox/commands/copy_command.rb

@@ -12,6 +12,10 @@ def self.command
           usage       'copy <sub-command> [options]'
           summary     'copy super command'
           description 'Copy 3scale entities between tenants'
+
+          run do |_opts, _args, cmd|
+            puts cmd.help
+          end
         end
       end
       add_subcommand(CopyServiceSubcommand)

lib/3scale_toolbox/commands/import_command.rb

@@ -13,6 +13,10 @@ def self.command
           usage       'import <sub-command> [options]'
           summary     'import super command'
           description 'Importing 3scale entities'
+
+          run do |_opts, _args, cmd|
+            puts cmd.help
+          end
         end
       end
       add_subcommand(ImportCsvSubcommand)

lib/3scale_toolbox/commands/update_command.rb

@@ -12,6 +12,10 @@ def self.command
           usage       'update <sub-command> [options]'
           summary     'update super command'
           description 'Update 3scale entities between tenants'
+
+          run do |_opts, _args, cmd|
+            puts cmd.help
+          end
         end
       end
       add_subcommand(UpdateServiceSubcommand)