ways to extend

docs/src/extend/ways-to-extend.md

@@ -19,7 +19,7 @@ Plugins are useful because your project may require some ESLint configuration th
 
 Often a plugin is paired with a shareable config, which applies a set of features from the plugin to a project.
 
-For example, ... TODO: come up w example. react prob easiest
+For example, [`eslint-plugin-react`](https://www.npmjs.com/package/eslint-plugin-react) is an ESLint plugin that include rules specifically for React projects. The rules include things like enforcing consistent usage of React component lifecycle methods and requiring the use of key props when rendering dynamic lists.
 
 To learn more about creating the things you can include in a plugin, refer to the following documentation:
 
@@ -29,8 +29,21 @@ To learn more about creating the things you can include in a plugin, refer to th
 
 ## Shareable Configs
 
+ESLint shareable configs are pre-defined configurations for ESLint that you can use in your projects.
+They bundle rules and other configuration together in an npm package. Anything that you can put in a `.eslintrc` configuration file can be put in a shareable config.
+
+For example, a popular shareable config is [eslint-config-airbnb](https://www.npmjs.com/package/eslint-config-airbnb), which contains a variety of rules in addition to some [parser options](../use/configure/language-options#specifying-parser-options). This is a set of rules for ESLint that is designed to match the style guide used by the [Airbnb JavaScript style guide](https://github.com/airbnb/javascript). By using the `eslint-config-airbnb` shareable config, you can automatically enforce the Airbnb style guide in your project without having to manually configure each rule.
+
+To learn more about creating a shareable config, refer to [Shareable Configs](shareable-configs).
+
 ## Custom Parsers
 
+ESLint custom parsers are a way to extend ESLint to support linting of new language features or custom syntax in your code. A parser is responsible for taking your code and transforming it into an abstract syntax tree (AST) that ESLint can then analyze and lint.
+
+ESLint ships with a built-in JavaScript parser (Espree), but custom parsers allow you to lint other languages or to extend the linting capabilities of the built-in parser.
+
+For example, the custom parser [@typescript-eslint/parser](https://typescript-eslint.io/architecture/parser/) extends ESLint to lint TypeScript code.
+
 ## Putting It All in a Package
 
 TODO: bit about how you can bundle all these things in a package