Documentation sections are missing from Resource Hub category pages #2533

Description

Resource Hub category pages skip sections when their resource group is
empty, with an exception for event.

However, docs sections get their content from categoriesConfig, not
from grouped resources. This causes configured documentation sections
to be skipped and leaves their navigation links without a target.

Affected categories:

• Frontend
• Backend
• Federation
• Security
• Monitoring

Steps to Reproduce

1. Open /resources/frontend/.
2. Select “Documentation” in the page navigation.
3. Observe that the documentation section is missing.

Expected Result

Configured documentation sections should render even when no resources
are grouped under docs. Their navigation links should point to the
rendered sections.

Actual Result

The documentation section is missing.

Additional Context