Add jira issue view PD-1234 --md

[codekiln]

I'm a big fan of using the GitHub CLI to save issues as markdown: gh issue 23 view > issue23.md will give me a markdown file with attributes and description of a GitHub issue. This is a big help for adding context to AI tools.

When using jira-cli, I'd love to be able to save an issue to a markdown file locally by doing jira issue view PD-1234 --md > PD-1234.md. Ideally, the result would be roughly the same as the equivalent github CLI command, where attributes were placed in the Markdown frontmatter in standard format.

This would be even more powerful in consort with Issue description in Markdown · ankitpokhrel/jira-cli · Discussion #617