update mariadb doc (#10)

Author: Zenzumai

docs/databases/mariadb.md

@@ -15,7 +15,7 @@ variable `CPHP_SERVICE_MARIADB` with the desired MariaDB version as value to you
 * ***10.3.2***
 
 E.g. if you need `MariaDB 10.3.2` in your Behat tests, go to the Testing Settings (step 2 of the Pipeline) and add the
-environment variable `CPHP_SERVICE_MARIADB = 5.7.20` to the Behat configuration.
+environment variable `CPHP_SERVICE_MARIADB = 10.3.2` to the Behat configuration.
 
 ### PHP Extensions