Add the Ruby implementation. (#152)

Author: artob

README.md

@@ -44,6 +44,7 @@ Why do we need yet another serialization format? Borsh is the first serializer t
 | C++                    | [borsh-cpp](https://github.com/Stolkerve/borsh-cpp) | *(work-in-progress)* |
 | C++20                    | [borsh-cpp20](https://github.com/israelidanny/borsh-cpp20) | *(work-in-progress)* |
 | Elixir                    | [borsh-ex](https://github.com/alexfilatov/borsh) | <a href="https://hex.pm/packages/borsh"><img src="https://img.shields.io/hexpm/v/borsh.svg?style=flat-square" alt="Latest released version" /></a> |
+| Ruby | [borsh.rb](https://github.com/dryruby/borsh.rb) | <a href="https://rubygems.org/gems/borsh"><img src="https://img.shields.io/gem/v/borsh?style=flat-square" alt="Latest released version" /></a> |
 
 ## Benchmarks