rename grouping expression input prop

Author: onlyexeption

src/app/services/export-excel/excel-export-sample-1/excel-export-sample-1.component.html

@@ -1,5 +1,5 @@
 <p class="grid__wrapper">
-  <igx-grid #igxGrid1 [data]="data" [groupingExpressions]='expr' [allowFiltering]="true" [cellSelection]="'single'"
+  <igx-grid #igxGrid1 [data]="data" [groupingExpressions]='groupExpressions' [allowFiltering]="true" [cellSelection]="'single'"
     [hideGroupedColumns]="true" [width]="'100%'" [height]="'700px'">
     <igx-column *ngFor="let c of columns" [sortable]="true" [field]="c.field" [header]="c.field" [width]="c.width"
         [hidden]='c.hidden' [groupable]='c.groupable' [movable]='true' [editable]="true" [dataType]='c.dataType'>