Move hint before content it refers to

EDUCATOR-1557

lms/templates/wiki/includes/editor_widget.html

 {% load i18n %}
-<textarea {{ attrs }}>{{ content }}</textarea>
 <p id="hint_id_content" class="help-block">
     {% blocktrans with start_link="<a id='cheatsheetLink' href='#cheatsheetModal' rel='leanModal'>" end_link="</a>" %}
         Markdown syntax is allowed. See the {{ start_link }}cheatsheet{{ end_link }} for help.
     {% endblocktrans %}
 </p>
+<textarea {{ attrs }}>{{ content }}</textarea>