docs: update rendering error page

[mihul87]

🔗 Linked issue

fixes:
#13987 Elaborate the "Rendering an error page" section
#14133 Custom Error Properties Are Not Retained

❓ Type of change

• [ x] 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

1. "Defined" the fatal error and explained when it occurs in the "Rendering an error page" section.
2. Explained how to get the errors with custom fields into error page.

📝 Checklist

• [x ] I have linked an issue or discussion.
• I have updated the documentation accordingly.

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