Multiple typos in documentation

[pboling]

      # @example
      #   class User
      #     include Dynamoid::Document
      #     field :email,          :string
      #     field :age,            :integer
      #     field :gender,         :string
      #     field :rank            :number
      #     table :key => :email
      #     global_secondary_index :hash_key => :age, :range_key => :gender
      #   end
      #   User.find_all_by_secondary_index(:age => 5, :range => {"rank.lte" => 10})

1. The :range_key => :gender should instead be :range_key => :rank.
2. Curly braces are required around the first hash param in:
   User.find_all_by_secondary_index(:age => 5, :range => {"rank.lte" => 10}), as
   User.find_all_by_secondary_index({:age => 5}, :range => {"rank.lte" => 10})