📝 chore(docs): add coding style guidelines & mention githook

CONTRIBUTING.md

@@ -22,6 +22,51 @@ If you're not sure how to contribute or need help with something, please don't h
 - Follow the [Conventional Commits Specification](https://www.conventionalcommits.org/en/v1.0.0/).
 - Use [gitmoji](https://gitmoji.dev/) – it's fun! 🫶
 
+## Coding Style Guidelines
+
+While we don't enforce a strict coding style, we appreciate it when contributions follow the existing code style of the project (e.g. indenting with 4 spaces). This makes the codebase easier to read and maintain. If you are making significant changes or additions, please try to maintain consistency with the current coding patterns and idioms.
+
+For JavaScript files, you can use [Biome](https://biomejs.dev/) to format your code.
+
+The CSS properties are sorted following [Concentric-CSS](https://github.com/brandon-rhodes/Concentric-CSS). If you use VSCode, the [Sort CSS](https://marketplace.visualstudio.com/items?itemName=piyushsarkar.sort-css-properties) extension makes this super easy.
+
+## Pre-commit Githook
+
+### Introduction
+
+We use a pre-commit githook to maintain code and file quality. [This script](https://github.com/welpo/tabi/blob/main/.githooks/pre-commit) performs a series of checks and updates before a commit is made.
+
+### Setting Up
+
+To use the pre-commit githook, run the following command from the root of the repository to configure the git hooks path and make the script executable:
+
+```bash
+git config core.hooksPath .githooks
+chmod +x .githooks/pre-commit
+```
+
+### Features
+
+The pre-commit githook performs the following actions:
+
+#### Automatic Updates
+
+- **Front Matter in Markdown Files**: Automatically updates the "updated" field in the front matter of `.md` files.
+- **PNG Compression**: Compresses PNG files using either [`oxipng`](https://github.com/shssoichiro/oxipng) or [`optipng`](https://optipng.sourceforge.net/), whichever is available on your system.
+- **Font Subsetting**: Runs `subset_font` if `config.toml` has been modified.
+
+#### Commit Checks
+
+The script prevents you from committing if:
+
+- The `.md` file is marked as a draft.
+- Any file contains a "TODO".
+- A JavaScript file is being committed without a corresponding minified version.
+- A minified JavaScript file is not as small as it could be. Requires installing [UglifyJS](https://github.com/mishoo/UglifyJS) and/or [terser](https://github.com/terser/terser).
+- `config.toml` and `theme.toml` have different numbers of lines in their `[extra]` sections.
+
+These checks are in place to ensure code quality and consistency throughout the project.
+
 ## Code of Conduct
 
 We expect all contributors to follow our [Code of Conduct](./CODE_OF_CONDUCT.md). Please be respectful and professional when interacting with other contributors.