The latest Rich-text editing feature of your answer text gives you markdown styling from a simple toolbar. The details are specified in the documentation. Having said that, you can implement a table using markdowns. From this SO answer,
If you add or edit your content directly in your knowledge base, use markdown formatting to create rich text content or change the markdown format content that is already in the answer. QnA Maker supports much of the markdown format to bring rich text capabilities to your content. However, the client application, such as a chatbot may not support the same set of markdown formats. It is important to test the client application's display of answers.
Also, keep in mind as to when to use rich-text editing and markdowns to best suit your needs.
Rich-text editing of answers allows you, as the author, to use a formatting toolbar to quickly select and format text.
Markdown is a better tool when you need to autogenerate content to create knowledge bases to be imported as part of a CI/CD pipeline or for batch testing.
Hope this helps.