refactor(*): change button text

Author: IMinchev64

src/app/grid/grid-sample-pinning-both-sides/grid-toolbar-pinning-both-sides.component.html

@@ -14,9 +14,9 @@
     >
         <igx-grid-toolbar>
             <igx-grid-toolbar-actions>
-                <button igxButton="contained" (click)="unpinColumn()"> Unpin Column </button>
-                <button igxButton="contained" (click)="pinLeft()"> Pin Left </button>
-                <button igxButton="contained" (click)="pinRight()"> Pin Right </button>
+                <button igxButton="contained" (click)="unpinColumn()"> Unpin Selected Columns </button>
+                <button igxButton="contained" (click)="pinLeft()"> Pin Selected Left </button>
+                <button igxButton="contained" (click)="pinRight()"> Pin Selected Right </button>
             </igx-grid-toolbar-actions>
         </igx-grid-toolbar>