improvement: markdown shortcuts

[mscolnick]

trafficstars

Adds a few markdown shortcuts

Bold (Mod-b)
Italic (Mod-i)
Convert to Link (Mod-k)
Convert to Ordered list (Mod-Shift-7)
Convert to Unordered list (Mod-Shift-8)
Convert to Blockquote (Mod-Shift-9)
Convert to Code (Mod-Shift-0)

Also improves pasting with a URL when selected and wrapping with a tick (`)

[vercel[bot]]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
marimo-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	May 17, 2024 2:00pm
marimo-storybook	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	May 17, 2024 2:00pm

[github-actions[bot]]

🚀 Development release published. You may be able to view the changes at https://marimo.app?v=0.6.1-dev1