CONTRIBUTING.md in stream-chat-ruby-3.3.0 vs CONTRIBUTING.md in stream-chat-ruby-3.4.0

@@ -12,10 +12,26 @@
 ```
 
 ### Run tests
 
 ```shell
-$ STREAM_KEY=my_api_key STREAM_SECRET=my_api_secret bundle exec rake spec
+$ STREAM_KEY=my_api_key STREAM_SECRET=my_api_secret bundle exec rspec spec
+```
+
+### Run specific test
+
+Add :focus tag on target test:
+
+```rb
+it 'can mark messages as read', :focus do
+    # test something
+end
+```
+
+And then run as following:
+
+```shell
+$ STREAM_KEY=myapi_key STREAM_SECRET=my_secret STREAM_CHAT_URL=http://127.0.0.1:3030 bundle exec rspec spec --tag focus
 ```
 
 ### Linters and type check
 
 We use [Rubocop](https://github.com/rubocop/rubocop) for linting and [Sorbet](https://sorbet.org/) for type checking.
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