Bug 1699426 - Remove margin-block for resetProfile learn more r=Gijs

Chatted with Emanuela about this and she noted that this shouldn't be such a
large gap here. Note: there should be a larger gap here between the text and
the buttons, but I think that applies to all modals. That should be a separate
patch, if you agree.

Differential Revision: https://phabricator.services.mozilla.com/D110131

toolkit/content/resetProfile.css

@@ -6,10 +6,6 @@
   padding: 10px;
 }
 
-#learnMoreDescription {
-  margin-block: 16px 0;
-}
-
 #infoTitle {
   font-weight: 600;
 }