Improved accessibility of search partial (#7233)

Author: jzazo

src/templates/partials/search.html

@@ -94,7 +94,7 @@
       {% endif %}
     </form>
     <div class="md-search__output">
-      <div class="md-search__scrollwrap" data-md-scrollfix>
+      <div class="md-search__scrollwrap" tabindex="0" data-md-scrollfix>
 
         <!-- Search results -->
         <div class="md-search-result" data-md-component="search-result">