Fix table layout for additionalProperties property

[neclimdul]

The generated documentation for disallowAdditionalPropertiesIfNotPresent doesn't work correctly because the markdown generator makes very simple tables that don't support new lines. This might be fixed with a more advanced generator but the simplest fix is just to not use the new line for now.

PR checklist

• Read the contribution guidelines.
• If contributing template-only or documentation-only changes which will change sample output, build the project before.
• Ran ./bin/utils/export_docs_generators.sh
• File the PR against the correct branch: master, 4.3.x, 5.0.x. Default: master.
• Copy the technical committee to review the pull request if your PR is targeting a particular programming language.

[neclimdul]

Note, the documentation between the description and the values duplicates a lot. Another helpful fix might be remove the duplication. I didn't feel familiar enough to start rewriting the documentation but if that sounds good I'll update the PR to remove the duplication.

[wing328]

@neclimdul thanks for the fix.

Sounds good to me. Looking forward to another PR from you to further improve the documentation 👍