Summary

Adds a new compatibility flag documentation entry for workflows_preserve_non_retryable_error_message.
When enabled, Workflow steps that throw a NonRetryableError will preserve the original error message and name on the thrown exception.

Screenshots (optional)

N/A

Documentation checklist

• Is there a changelog (https://developers.cloudflare.com/changelog/) entry (guidelines (https://developers.cloudflare.com/style-guide/documentation-content-strategy/content-types/changelog/))? If you don't add one for something awesome and new (however small) — how will our customers find out? Changelogs are automatically posted to RSS feeds (https://developers.cloudflare.com/fundamentals/new-features/available-rss-feeds/), the Discord (https://discord.com/channels/595317990191398933/1040420029080018945), and X (https://x.com/CFchangelog).
• The change adheres to the documentation style guide (https://developers.cloudflare.com/style-guide/).
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• Files which have changed name or location have been allocated redirects (https://developers.cloudflare.com/pages/configuration/redirects/#per-file).