[ruby/yarp] Add a CHANGELOG

https://github.com/ruby/yarp/commit/b490ff0919

lib/yarp/yarp.gemspec

@@ -12,6 +12,7 @@ Gem::Specification.new do |spec|
 
   spec.require_paths = ["lib"]
   spec.files = [
+    "CHANGELOG.md",
     "CODE_OF_CONDUCT.md",
     "CONTRIBUTING.md",
     "LICENSE.md",