Export to Markdown for Jira Cloud allows you to easily export your Jira issues to Markdown.
To get started, open an issue and click on the three dots in the top-right of the Jira issue.
Then select "Export Markdown" and you'll be shown a modal dialog.
From the "Options" menu in the modal dialog, you can configure the following options:
Enabling this option will include user comments in the exported Markdown
Enabling this option will include issue fields in the generated output (such as issue status, project and components)
Enabling this option will include HTML in the generated output for content that can't be represented in Markdown (such as underline, superscript and subscript)
Once you're happy with the Markdown preview in the modal, you can then download result, or copy it to your clipboard.