Add setup example for ruby_event_store-rom

contrib/ruby_event_store-rom/README.md

@@ -7,3 +7,47 @@ A Ruby Object Model (ROM) implementation of events repository for [Ruby Event St
 This version of the ROM adapter supports [rom-sql](https://github.com/rom-rb/rom-sql) at this time. It is an alternative to the ActiveRecord `EventRepository` implementation used in `rails_event_store` gem.
 
 [Read the docs to get started.](http://railseventstore.org/docs/repository/)
+
+## Setup
+
+### Rake tasks
+
+Add to your `Rakefile`
+
+```ruby
+require "ruby_event_store/rom/rake_task"
+```
+
+### Database migration
+
+A migration template can be found in [db/migrate/20210806000000_create_ruby_event_store_tables.rb](db/migrate/20210806000000_create_ruby_event_store_tables.rb).
+
+You can choose the type of the `data` and `metadata` columns by using the `DATA_TYPE` environment variable:
+
+```shell
+rake db:migrate DATA_TYPE='text' # or
+rake db:migrate DATA_TYPE='json' # or
+rake db:migrate DATA_TYPE='jsonb'
+```
+
+### Application
+
+```ruby
+# config/initializers/ruby_event_store.rb
+
+config = ROM::Configuration.new(:sql, ENV.fetch("DATABASE_URL"))
+RES_ROM_CONTAINER = RubyEventStore::ROM.setup(config)
+
+repository = RubyEventStore::ROM::EventRepository.new(
+  rom: RES_ROM_CONTAINER,
+  serializer: JSON # this setting is optional. Recommended when `data` and `metadata` are json(b) columns. 
+)
+
+event_store = RubyEventStore::Client.new(repository: repository)
+
+event_store.subscribe_to_all_events(RubyEventStore::LinkByCausationId.new(event_store: event_store))
+event_store.subscribe_to_all_events(RubyEventStore::LinkByCorrelationId.new(event_store: event_store))
+event_store.subscribe_to_all_events(RubyEventStore::LinkByEventType.new(event_store: event_store))
+
+EVENT_STORE = event_store
+```