Add link to selenium.cr (#633)

Signed-off-by: Michael Nikitochkin <[email protected]>

README.md

@@ -494,6 +494,7 @@ described in [RFC 8032]
  * [microtest](https://github.com/Ragmaanir/microtest) - Small opinionated testing library focusing on power asserts
  * [minitest.cr](https://github.com/ysbaddaden/minitest.cr) - Library for unit tests and assertions
  * [mocks.cr](https://github.com/waterlink/mocks.cr) - Mocking library for Crystal
+ * [selenium.cr](https://github.com/crystal-loot/selenium.cr) - Selenium client for interacting with web pages for browser automation
  * [Spec](https://crystal-lang.org/api/Spec.html) - spec framework (Crystal stdlib)
  * [spectator](https://gitlab.com/arctic-fox/spectator) - Feature rich spec framework that uses the modern expect syntax
  * [timecop.cr](https://github.com/crystal-community/timecop.cr) - Library for mocking with `Time.now`. Inspired by the [timecop ruby gem](https://github.com/travisjeffery/timecop)