Adds support for nested args in cli's help (redis#8074)

See redis/redis-doc#1443

Also allows nameless commands.

Author: itamarhaber

utils/generate-command-help.rb

@@ -25,9 +25,15 @@
 ].freeze
 
 def argument arg
-  name = arg["name"].is_a?(Array) ? arg["name"].join(" ") : arg["name"]
-  name = arg["enum"].join "|" if "enum" == arg["type"]
-  name = arg["command"] + " " + name if arg["command"]
+  if "block" == arg["type"]
+    name = arg["block"].map do |entry|
+      argument entry
+    end.join " "
+  else
+    name = arg["name"].is_a?(Array) ? arg["name"].join(" ") : arg["name"]
+    name = arg["enum"].join "|" if "enum" == arg["type"]
+    name = arg["command"] + (name ? " " + name : "") if arg["command"]
+  end
   if arg["multiple"]
     name = "#{name} [#{name} ...]"
   end