Add code highlighting to volume mount example

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mysql/content.md

@@ -92,7 +92,7 @@ The Docker documentation is a good starting point for understanding the differen
 1.	Create a data directory on a suitable volume on your host system, e.g. `/my/own/datadir`.
 2.	Start your `%%REPO%%` container like this:
 
-	docker run --name some-%%REPO%% -v /my/own/datadir:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=my-secret-pw -d %%REPO%%:tag
+		docker run --name some-%%REPO%% -v /my/own/datadir:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=my-secret-pw -d %%REPO%%:tag
 
 The `-v /my/own/datadir:/var/lib/mysql` part of the command mounts the `/my/own/datadir` directory from the underlying host system as `/var/lib/mysql` inside the container, where MySQL by default will write its data files.