Make it explicit that we are referencing official Vue guidelines

doc/development/new_fe_guide/development/testing.md

@@ -56,7 +56,7 @@ Unit tests are on the lowest abstraction level and typically test functionality
   <summary>Vue components</summary>
   Computed properties, methods, and lifecycle hooks can be considered an implementation detail of components and don't need to be tested.
   They are implicitly covered by component tests.
-  The <a href="https://vue-test-utils.vuejs.org/guides/#getting-started">official guidelines</a> suggest the same.
+  The <a href="https://vue-test-utils.vuejs.org/guides/#getting-started">official Vue guidelines</a> suggest the same.
 </details>
 
 ### What to mock in unit tests