data: Mark release descriptions as untranslatable

[ghost]

GNOME automatically excludes release descriptions on Damned Lies (GNOME Translation Platform). It's a good practice to follow the GNOME way.

This can streamline the translation process, allowing translators to focus their efforts on more critical and user-facing aspects of the application.

[hugolabe]

Thanks @sabriunal

I usually remove release descriptions from the wike.pot file to minimize the work of translators, but this way it's easier for me.