Add more explicit explanations about author attribution and fediverse:creator (#32383)

app/javascript/styles/mastodon/forms.scss

@@ -23,6 +23,8 @@ code {
   position: relative;
   overflow: hidden;
   height: 160px;
+  max-width: 566px;
+  margin-inline: auto;
 
   &::after {
     content: '';