Remove outdated 30-Day Trial (POC) recipe reference

[jasnoyaeger]

Summary

• Remove the "Reference Example" admonition from the Tenant Recipes page that referenced the "30-Day Trial (POC)" recipe, which was removed in VergeOS 26.0

Context

• The 26.0 release notes confirm: "Removed 30-day POC tenant recipe (no longer maintained)"
• Validated against a live VergeOS 26.1.2 system — Tenant Recipes page shows zero results, confirming the recipe is gone
• The "Tenant Crash Cart" recipe (suggested as a replacement in the issue) is a VM Recipe, not a Tenant Recipe, so it would not be an appropriate substitute reference

Test plan

• Verify the tenant recipes page renders correctly at /product-guide/automation/tenant-recipes/
• Confirm the Database Context section flows naturally into the "Modify a Recipe" section

Closes #393

🤖 Generated with Claude Code

[jasnoyaeger]

This PR also addresses #388, which is a duplicate of #393.