Improve the way to distinguish optional from mandatory fields

[sschuberth]

Whether a field is optional / mandatory should not be part of the field's description (like it currently is e.g. for an organization's description), but be an inherent UI part of the form itself.

Some random links on the matter:

• https://www.nngroup.com/articles/required-fields/
• https://adamsilver.io/blog/how-to-highlight-required-and-optional-form-fields/ (which mostly disagrees with the above 😆)

Personally, I regard everything as mandatory in a form unless noted otherwise, so I'd go for only marking optional fields. Doing that as a dimmed suffix to the field's name, or as a dimmed text that's only shown as long as the field is empty seems to be to most reasonable to me.