[9.x] add a small tip on how to clear the config cache (#8758)

* add a small tip on how to clear the config cache

* Update configuration.md

---------

Co-authored-by: Taylor Otwell <taylor@laravel.com>

Author: Seryojik

configuration.md

@@ -197,6 +197,12 @@ To give your application a speed boost, you should cache all of your configurati
 
 You should typically run the `php artisan config:cache` command as part of your production deployment process. The command should not be run during local development as configuration options will frequently need to be changed during the course of your application's development.
 
+The `config:clear` command may be used to purge the cached configuration:
+
+```shell
+php artisan config:clear
+```
+
 > **Warning**  
 > If you execute the `config:cache` command during your deployment process, you should be sure that you are only calling the `env` function from within your configuration files. Once the configuration has been cached, the `.env` file will not be loaded; therefore, the `env` function will only return external, system level environment variables.