minor tweak to note xref display

app/db/README.md

@@ -56,3 +56,4 @@ To get more help on the Angular CLI use `ng help` or go check out the [Angular C
 - Test note persistence
 - Test note search
 - Make card icons configurable (for future)
+- remove old ionic project

app/db/src/app/search/components/note/note-card.component.html

@@ -16,7 +16,7 @@
   <ngx-md class="markdown" *ngIf="cardItem.data">{{
     cardItem.data.content
   }}</ngx-md>
-  <mat-expansion-panel>
+  <mat-expansion-panel *ngIf="cardItem.data.xref && cardItem.data.xref !== ''">
     <mat-expansion-panel-header>
       <mat-panel-title>
         Cross References