doc: Add more features to README.md

Author: KSXGitHub

README.md

@@ -57,6 +57,8 @@ The benchmark was generated by [a GitHub Workflow](https://github.com/KSXGitHub/
 * Relative comparison of separate files.
 * Extensible via the library crate or JSON interface.
 * Optional progress report.
+* Customize tree depth.
+* Customize chart size.
 
 ## Limitations