[meta] CONTRIBUTING.md: add resources for newcomers

Author: azyzz228

CONTRIBUTING.md

@@ -18,6 +18,15 @@ When opening an [issue](#issues):
 
 Remember, you don't need to do it all yourself; any of these are helpful! 😎
 
+## How to get started
+
+If you are new to `eslint`, below are a few resources that will help you to familiarize yourself with the project.
+
+- Watch [this presentation](https://www.youtube.com/watch?v=2W9tUnALrLg) to learn the fundamental concept of Abstract Syntax Trees (AST) and the way `eslint` works under the hood.
+- Familiarize yourself with the [AST explorer](https://astexplorer.net/) tool. Look into rules in `docs/rules`, create patterns in the rules, then analyze its AST.
+- Explore the blog posts on how to create a custom rule. [One blog post](https://blog.yonatan.dev/writing-a-custom-eslint-rule-to-spot-undeclared-props/). [Second blog post](https://betterprogramming.pub/creating-custom-eslint-rules-cdc579694608).
+- Read the official `eslint` [developer guide](https://eslint.org/docs/latest/developer-guide/architecture/).
+
 ## Issues
 
 ### Search open + closed issues for similar cases