added "what links here" widget

src/routes/api/attributes.js

@@ -157,6 +157,12 @@ async function deleteRelation(req) {
     }
 }
 
+async function getTargetRelations(req) {
+    const note = await repository.getNote(req.params.noteId);
+
+    return await note.getTargetRelations();
+}
+
 module.exports = {
     updateNoteAttributes,
     updateNoteAttribute,
@@ -165,5 +171,6 @@ module.exports = {
     getValuesForAttribute,
     getEffectiveNoteAttributes,
     createRelation,
-    deleteRelation
+    deleteRelation,
+    getTargetRelations
 };