diff --git a/.gitattributes b/.gitattributes
index 44e9c84..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
-/tests/                     export-ignore
-/docs/                      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 e43e889..9e8d5b6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,8 +1,9 @@
-/.phpunit.cache/
 /vendor/
-/.php-cs-fixer.cache
 /composer.lock
+/.phpunit.cache/
+/.phpunit.result.cache
+/.php-cs-fixer.cache
+/coverage/
+/coverage.xml
+
 src/**/composer.lock
-/phpstan.neon
-/phpunit.xml
-/clover.xml
diff --git a/README.md b/README.md
index 82e1072..6c48212 100644
--- a/README.md
+++ b/README.md
@@ -213,10 +213,34 @@ console.log('Hello');
 
 [Documentation](https://altophp.com/commonmark/docs/extensions/tabs) · [GitHub](https://github.com/alto/commonmark/tree/main/src/Extension/Tabs) · [Packagist](https://packagist.org/packages/alto/commonmark-tabs)
 
+## Contributing
+
+Contributions of all kinds are welcome. Visit the
+[project on GitHub](https://github.com/altophp/commonmark) to
+[report a bug](https://github.com/altophp/commonmark/issues/new),
+[suggest a feature](https://github.com/altophp/commonmark/issues/new), or
+[open a pull request](https://github.com/altophp/commonmark/pulls).
+
+Before submitting code, run:
+
+```bash
+# Runs PHP CS Fixer, PHPStan, and PHPUnit
+composer qa
+```
+
+Changes to public behavior should include tests and documentation.
+
 ## Support
 
-If Alto CommonMark is useful to your project, [sponsoring on GitHub](https://github.com/sponsors/smnandre) is a great way to support continued development — and it's always appreciated.
+ALTO CommonMark 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/commonmark) also helps.
 
 ## License
 
-MIT. See [LICENSE](LICENSE).
+ALTO CommonMark is released by [ALTO PHP](https://altophp.com) under the
+[MIT License](LICENSE).