feat(docs): enhance docs with GitHub flavors markdown

Signed-off-by: Son Nguyen <[email protected]>

Author: hoangsonww

.github/CONTRIBUTING.md

@@ -0,0 +1,49 @@
+# Contributing to FastFetch
+
+Thanks for your interest in contributing! Please take a moment to read this guide.
+
+## Getting Started
+
+1. Fork the repository and clone your fork (adjust the URL to your fork as needed):
+
+   ```bash
+   git clone <[email protected]:your-username/FastFetch.git>
+   cd FastFetch
+   ```
+
+2. Install dependencies:
+
+   ```bash
+   npm ci
+   ```
+
+3. Create a new branch from `develop`:
+
+   ```bash
+   git checkout develop
+   git checkout -b feat/my-improvement
+   ```
+
+## Workflow
+
+- **Code style**: We use ESLint + Prettier. Your editor should auto-format on save.
+- **Testing**: Add/update Jest tests under `__tests__/`.
+- **Commit messages**: Use [Conventional Commits](https://www.conventionalcommits.org).
+
+  ```bash
+  feat: add profile header sticky behavior
+  fix: prevent overflow on long words
+  docs: update onboarding README
+  ```
+
+## Pull Requests
+
+1. Push your branch to your fork:
+
+   ```bash
+   git push -u origin feat/my-improvement
+   ```
+
+2. Open a PR against `develop` and fill out the PR template.
+3. Ensure CI passes (lint, tests, build).
+4. Respond to review feedback—thank you!