diff --git a/.gitattributes b/.gitattributes
index 8e67605..f495aed 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1,11 +1,15 @@
 * text=auto eol=lf
 
-/.git*                      export-ignore
-/.php-cs-fixer.dist.php     export-ignore
-/phpstan.neon.dist          export-ignore
-/phpunit.xml.dist           export-ignore
-/docs/                      export-ignore
-/tests/                     export-ignore
+/.gitattributes              export-ignore
+/.github                     export-ignore
+/.gitignore                  export-ignore
+/.php-cs-fixer.dist.php      export-ignore
+/composer.lock               export-ignore
+/docs                        export-ignore
+/phpstan.neon.dist           export-ignore
+/phpunit.xml.dist            export-ignore
+/tests                       export-ignore
 
-/tests/**                   linguist-vendored
-/docs/**                    linguist-documentation
+/docs/**                     linguist-documentation
+/tests/Fixtures/**           -linguist-detectable
+/tests/fixtures/**           -linguist-detectable
diff --git a/.gitignore b/.gitignore
index 9f48e4a..d6c64c9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,8 +1,7 @@
-/.phpunit.cache/
-/var/
 /vendor/
+/composer.lock
+/.phpunit.cache/
+/.phpunit.result.cache
 /.php-cs-fixer.cache
+/coverage/
 /coverage.xml
-/composer.lock
-/phpstan.neon
-/phpunit.xml
diff --git a/README.md b/README.md
index b1f0100..10a0459 100644
--- a/README.md
+++ b/README.md
@@ -356,20 +356,34 @@ $file->headers['index'];  // 'index abcdef..123456 100644'
 - [Errors](docs/errors.md): recover from rejected inputs and patches.
 - [Complete documentation](docs/index.md): review the package scope and every guide.
 
-## Testing
+## Contributing
 
-Run the test suite:
+Contributions of all kinds are welcome. Visit the
+[project on GitHub](https://github.com/altophp/code-diff) to
+[report a bug](https://github.com/altophp/code-diff/issues/new),
+[suggest a feature](https://github.com/altophp/code-diff/issues/new), or
+[open a pull request](https://github.com/altophp/code-diff/pulls).
+
+Before submitting code, run:
 
 ```bash
-vendor/bin/phpunit
+# Runs PHP CS Fixer, PHPStan, and PHPUnit
+composer qa
 ```
 
-Run tests with coverage:
+Changes to public behavior should include tests and documentation.
 
-```bash
-vendor/bin/phpunit --coverage-text
-```
+## Support
+
+ALTO Code Diff is open source and independently maintained by
+[Simon André](https://smnandre.dev). If it is useful to your work, you can
+support its continued development through
+[GitHub Sponsors](https://github.com/sponsors/smnandre).
+
+Sharing the package or
+[starring it on GitHub](https://github.com/altophp/code-diff) also helps.
 
 ## License
 
-This project is licensed under the [MIT License](./LICENSE).
+ALTO Code Diff is released by [ALTO PHP](https://altophp.com) under the
+[MIT License](LICENSE).