add documentation from readme to Errors class yard doc

lib/lunchmoney/errors.rb

@@ -2,7 +2,23 @@
 # frozen_string_literal: true
 
 module LunchMoney
-  # This class is used to represent errors returned directly from the LunchMoney API
+  # This class is used to represent errors returned directly from the LunchMoney API. This class has been set up to act
+  # like an array, delegating a lot of common array getter methods directly to messages for you.
+  # @example
+  #   api = LunchMoney::Api.new
+  #   response = api.categories
+  #
+  #   response.class
+  #   => LunchMoney::Errors
+  #
+  #   response.first
+  #   => "Some error returned by the API"
+  #
+  #   response.empty?
+  #   => false
+  #
+  #   response[0]
+  #   => "Some error returned by the API"
   class Errors
     sig { returns(T::Array[String]) }
     attr_accessor :messages