manual: minor update in docker run instruction

manual/Starting_the_server/Docker.md

@@ -18,9 +18,8 @@ The image comes with libraries for easy indexing data from MySQL, PostgreSQL XML
 
 The below is the simplest way to start Manticore in a container and log in to it via mysql client:
 
-
 ```bash
-docker run -e EXTRA=1 --name manticore --rm -d manticoresearch/manticore && until docker logs manticore 2>&1 | grep -q "accepting connections"; do sleep 1; done && docker exec -it manticore mysql && docker stop manticore
+docker run -e EXTRA=1 --name manticore --rm -d manticoresearch/manticore && echo "Waiting for Manticore docker to start. Consider mapping the data_dir to make it start faster next time" && until docker logs manticore 2>&1 | grep -q "accepting connections"; do sleep 1; echo -n .; done && echo && docker exec -it manticore mysql && docker stop manticore
 ```
 
 Note that upon exiting the MySQL client, the Manticore container will be stopped and removed, resulting in no saved data. For information on using Manticore in a production environment, please see below.