src/app/item-page: adjust space in simple item view

The Bootstrap grid is composed of 12 columns, and we are only using
10 on medium displays and up (4+6). Adjust to use 4+8 to allow more
space to be used for things like abstracts and citations.

Author: alanorth

src/app/item-page/simple/item-types/untyped-item/untyped-item.component.html

@@ -55,7 +55,7 @@
       [label]="'item.page.publisher'">
     </ds-generic-item-page-field>
   </div>
-  <div class="col-12 col-md-6">
+  <div class="col-12 col-md-8">
     <ds-item-page-abstract-field [item]="object"></ds-item-page-abstract-field>
     <ds-generic-item-page-field [item]="object"
       [fields]="['dc.description']"