Update "contributing guidelines" link (#1390)

README.md

@@ -382,7 +382,7 @@ stopwords = [
 ]
 ```
 
-Refer to the default [gitleaks config](https://github.com/zricethezav/gitleaks/blob/master/config/gitleaks.toml) for examples or follow the [contributing guidelines](https://github.com/zricethezav/gitleaks/blob/master/README.md) if you would like to contribute to the default configuration. Additionally, you can check out [this gitleaks blog post](https://blog.gitleaks.io/stop-leaking-secrets-configuration-2-3-aeed293b1fbf) which covers advanced configuration setups.
+Refer to the default [gitleaks config](https://github.com/zricethezav/gitleaks/blob/master/config/gitleaks.toml) for examples or follow the [contributing guidelines](https://github.com/gitleaks/gitleaks/blob/master/CONTRIBUTING.md) if you would like to contribute to the default configuration. Additionally, you can check out [this gitleaks blog post](https://blog.gitleaks.io/stop-leaking-secrets-configuration-2-3-aeed293b1fbf) which covers advanced configuration setups.
 
 ### Additional Configuration