Rendering of service descriptions on the main page

[hgstp]

Issue description:

I created the service item https://portal.mardi4nfdi.de/wiki/Item:Q6544359 and used in the description the same formatting as in https://portal.mardi4nfdi.de/wiki/Item:Q6503328.
On the service overview page https://portal.mardi4nfdi.de/wiki/MaRDI_Services, the description isn't properly rendered. On this page, the behavior is consistent over all service items, which structured the description in this way.
On the main page, I don't see the h2 heading for the service https://portal.mardi4nfdi.de/wiki/Item:Q6503328, but it is there for https://portal.mardi4nfdi.de/wiki/Item:Q6544359.

TODOS:

Adjust the rendering such that descriptions are displayed as, e.g., on https://portal.mardi4nfdi.de/wiki/Service:6503328, or decide that we should only use plain text.

Acceptance-Criteria

Checklist for this issue:

• Assignee has been set for this issue
• All fields of the issue have been filled
• Issue has been assigned to the main project
• Code was merged
• Feature branch has been deleted and issues were updated / closed
• Issue is tracked by an epic, or the label 'non-epic' is set to the issue.

[timconrad]

I introduced a statement "summary" in the item (see https://portal.mardi4nfdi.de/wiki/Item:Q6544359 ).

If "summary" is present, this is used instead of the "description" on the front page (i.e. https://portal.mardi4nfdi.de/ ).

This needs to be documented in the manual.

[timconrad]

Fixed.