Add blockquote style

Signed-off-by: Émile Ré <emile@getprobo.com>

pkg/docgen/template.html

@@ -363,6 +363,12 @@
             max-width: 100%;
             height: auto;
         }
+
+        .document-content blockquote {
+            border-left: 4px solid #ccc;
+            padding-left: 16px;
+            margin: 12px 0;
+        }
     </style>
     <script>{{.MermaidJS}}</script>
     <script>