docs(design): Add general content guidelines for error messages

[chris-at-jobber]

Motivations

Designers often seek general guidance on error messaging. While we have component-specific guides, we don't have them generalized.

Changes

Added

• Guidance on general error messaging to Voice and Tone

Testing

View docs locally or in the Cloudflare build

---

In Atlantis we use Github's built in pull request reviews.

[cloudflare-workers-and-pages[bot]]

Deploying atlantis with    Cloudflare Pages

Latest commit:	4a5f446
Status:	✅  Deploy successful!
Preview URL:	https://84579639.atlantis.pages.dev
Branch Preview URL:	https://content-guides-for-errors.atlantis.pages.dev

View logs