User Settings - Category description should be displayed to the users

[Gilbertdelyon]

When you add some custom fields in user profile form, you can group them in categories.
Each category has a "description" field.
As far as I can see, this field is not used anywhere else (May be I am wrong?)

It would be nice to have:

• a markdown or simple html field instead of a basic text area
• a radio or select case where you could set the display of this text at the top of the form, so that you could instruct the user about the specific custum fields.