If you click context menu icon of this addon in markdown table. It enable editable of markdown table.
At the same time create button that is copy text of markdown style of editing table.

Details. (You can watch gif of actually using addon)
https://qiita.com/amanoese/items/b81047db612b388b2eb0

Install

• License: MIT License
• Weekly downloads: 0
• Average daily users: 9
• Rating: 0/5 of 0 ratings
• Created: 2018-10-16 18:51:52
• Last updated: 2019-01-31 16:10:09
• Homepage: https://twitter.com/amanoese
• Support site and email
• Orig: https://addons.mozilla.org/en-US/firefox/addon/markdown-table-editer/
• API: {00bd23d9-88fd-4f55-a104-66b35f8ea830}