Fix URL Scan notes section

What does this MR do?

The Notes are not showing in the notes section of the URL Scan instructions. This seems to be because the requirement of a list to be surrounded by space is incompatible with the Note notation, that requiring the note text to be on the subsequent line to the note header NOTE: **Note:**.

It seems that in other documentation when there are multiple notes, each note is shown in a separate block. An example of that would be the File hooks page

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team