docs(pivotGrid): fixed property typo

Author: tishko0

src/app/pivot-grid/pivot-layout/pivot-layout.component.html

@@ -1,6 +1,6 @@
 <div class="pivot-container">
     <igx-pivot-grid #grid1 [data]="data" [height]="'850px'" [pivotConfiguration]="pivotConfig" [rowSelection]="'single'"
-        [superCompactMode]="true" [defaultExpandState]='true' [pivotUi]="pivotUi">
+        [superCompactMode]="true" [defaultExpandState]='true' [pivotUI]="pivotUI">
     </igx-pivot-grid>
     <igx-pivot-data-selector [grid]="grid1"></igx-pivot-data-selector>
 </div>