NAME not SLUG should be used to describe an unsanitised url

What does this MR do?

Example has a typo, used the incorrect SLUG variable in example text describing NAME.

$CI_COMMIT_REF_NAME.example.com would generate the included example of https://100-do-the-thing.example.com

This description is intended to contrast the actual code, which is safer but less user-friendly, as follows:

  environment:
    name: review/$CI_COMMIT_REF_NAME
    url: https://$CI_ENVIRONMENT_SLUG.example.com

Does this MR meet the acceptance criteria?

Documentation issue only.

Conformity

• [-] Documentation created/updated or [follow-up

Availability and Testing

Needs to be reviewed that this was not a misunderstanding the example mentioned, we don't want to add more confusion!

Security

No code change to be included.