Add Changelog entry

Author: JuanVqz

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * <INSERT YOUR FEATURE OR BUGFIX HERE>
 
+* [FEATURE: Generate JSON report in background](https://github.com/fastruby/skunk/pull/119)
 * [ENHANCEMENT: Better test suite with more relaxed console output expectation](https://github.com/fastruby/skunk/pull/117)
 * [ENHANCEMENT: Use minitest 5.22.x (also, stop testing with Ruby 2.4 and 2.5)](https://github.com/fastruby/skunk/pull/115)
 

README.md

@@ -123,6 +123,10 @@ To only run skunk on specific folders, pass a list of directories in the command
 
 `skunk app lib`
 
+### Generate JSON report in background
+
+When the Skunk command is run, it will generate a JSON report file in the `RubyCritic::Config.root` location.
+
 ### Comparing feature branches
 
 When working on new features, run skunk against your feature branch to check if the changes are improving or decreasing the code quality of the project.