Add link component from gitlab-ui

app/assets/javascripts/boards/components/modal/lists_dropdown.vue

 <script>
+import Link from '@gitlab-org/gitlab-ui/dist/components/base/link';
 import ModalStore from '../../stores/modal_store';
 
 export default {
+  components: {
+    'gl-link': Link,
+  },
   data() {
     return {
       modal: ModalStore.store,
@@ -38,7 +42,7 @@ export default {
           v-for="(list, i) in state.lists"
           v-if="list.type == 'label'"
           :key="i">
-          <a
+          <gl-link
             :class="{ 'is-active': list.id == selected.id }"
             href="#"
             role="button"
@@ -48,7 +52,7 @@ export default {
               class="dropdown-label-box">
             </span>
             {{ list.title }}
-          </a>
+          </gl-link>
         </li>
       </ul>
     </div>

app/assets/javascripts/vue_shared/components/markdown/toolbar.vue

 <script>
+  import Link from '@gitlab-org/gitlab-ui/dist/components/base/link';
+
   export default {
+    components: {
+      'gl-link': Link,
+    },
     props: {
       markdownDocsPath: {
         type: String,
@@ -28,30 +33,30 @@
   <div class="comment-toolbar clearfix">
     <div class="toolbar-text">
       <template v-if="!hasQuickActionsDocsPath && markdownDocsPath">
-        <a
+        <gl-link
           :href="markdownDocsPath"
           target="_blank"
           tabindex="-1"
         >
           Markdown is supported
-        </a>
+        </gl-link>
       </template>
       <template v-if="hasQuickActionsDocsPath && markdownDocsPath">
-        <a
+        <gl-link
           :href="markdownDocsPath"
           target="_blank"
           tabindex="-1"
         >
           Markdown
-        </a>
+        </gl-link>
         and
-        <a
+        <gl-link
           :href="quickActionsDocsPath"
           target="_blank"
           tabindex="-1"
         >
           quick actions
-        </a>
+        </gl-link>
         are supported
       </template>
     </div>