Docs: Feedback for Start a Local Cluster in Docker

Hi, I have some feedback about [this page](https://github.com/hazelcast/hz-docs/edit/main/docs/modules/getting-started/pages/get-started-docker.adoc)

under SQL in step 2. Create a map and add data to it. We put two commands in there. So if you copy and paste the whole block, it will error out with

> The command must contain a single statement.

You have to copy and paste the commands separately.

So separate them into
`CREATE MAPPING my_distributed_map TYPE IMap OPTIONS ('keyFormat'='varchar','valueFormat'='varchar');`
and then a new step separately
```
SINK INTO my_distributed_map VALUES
('1', 'John'),
('2', 'Mary'),
('3', 'Jane');
```
Also on that page where it says

> Step 6. Scale your Cluster

in number 4, the screenshot calls out backups. It says:

> You should see that entries and their backups are distributed evenly across each member.

Those don't appear in the dashboard in MC 5.7 that I can see.

Open docs/modules/getting-started/pages/get-started-docker.adoc and review the SQL in Step 2 and the dashboard wording in Step 6, number 4. Check the instructions against the reported single-statement error and Hazelcast Management Center 5.7, then update the commands and backup-distribution guidance so the page matches the current UI and workflow.

Written by the indexing model from the issue text.