Update README.md

README.md

@@ -102,9 +102,16 @@ inconsistencies (that aren't a result of legacy APIs) file an issue.
 
 ## Contribution Guidelines
 - Ensure your changes pass the tests below.
-- To ensure the code follows Deno's formatting guidelines, use the built-in deno fmt command. This will automatically format your TypeScript files to match Deno's code style. Run: ``sh deno fmt``
+- To ensure the code follows Deno's formatting guidelines, use the built-in deno fmt command. This will automatically format your TypeScript files to match Deno's code style.
+```sh
+deno fmt
+```
+-Before submitting any pull requests, make sure to run deno fmt to keep the repository consistent with the project's style
 - When implementing new features for Deno DOM, ensure that the standard algorithm outlined by the [DOM Living Standard](https://dom.spec.whatwg.org/) is followed. Any deviations from the spec should be documented clearly in the code and pull request descriptions.
 
+## Feature Compatiblity
+If a feature relies on new JavaScript capabilities (e.g., ES6+ features like optional chaining or private class members), ensure that the feature remains compatible with the target runtime (Deno). Use browser compatibility data from MDN Web Docs to check for any potential issues.
+
 ## Running tests
 
 To run tests (excluding WPT tests) use the following for WASM