Add info about batching to reading docs
Add info about batching to reading docs

[#369]

arkency/rails_event_store,RailsEventStore/rails_event_store,arkency/rails_event_store,RailsEventStore/rails_event_store,arkency/rails_event_store,RailsEventStore/rails_event_store,mpraglowski/rails_event_store,arkency/rails_event_store,mpraglowski/rails_event_store,mpraglowski/rails_event_store,mpraglowski/rails_event_store,RailsEventStore/rails_event_store