feat(issue-priority): Add new page for issue priority

[malwilley]

Pre-merge checklist

• [ ] Checked Vercel preview for correctness, including links
• [ ] PR was reviewed and approved by any necessary SMEs
• [ ] PR was reviewed and approved by a member of the Sentry docs team

Description of changes

Issue priority will be released to EA users soon, so we need a docs page to explain the new concept. This docs page will be linked in the UI here:

[vercel[bot]]

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

Name	Status	Preview	Comments	Updated (UTC)
sentry-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Apr 15, 2024 6:07pm

[codecov[bot]]

Bundle Report

Changes will increase total bundle size by 514 bytes :arrow_up:

Bundle name	Size	Change
sentry-docs-edge-server	3.41kB	60 bytes :arrow_down:
sentry-docs-client	5.52MB	6 bytes :arrow_down:
sentry-docs-server	5.96MB	580 bytes :arrow_up: