chore(IgxCell): add comment that explain the fix for issue #6517

Author: ddincheva

projects/igniteui-angular/src/lib/grids/cell.component.ts

@@ -620,6 +620,13 @@ export class IgxGridCellComponent implements OnInit, OnChanges, OnDestroy {
         if (this.editable && editMode && !this.row.deleted) {
             if (editableCell) {
                 this.gridAPI.update_cell(editableCell, editableCell.editValue);
+                /* This check is related with the following issue #6517:
+                 * when edit cell that belongs to a column which is sorted and press tab,
+                 * the next cell in edit mode is with wrong value /its context is not updated/;
+                 * So we reapply sorting before the next cell enters edit mode.
+                 * Also we need to keep the notifyChanges below, because of the current
+                 * change detection cycle when we have editing with enabled transactions
+                 */
                 if (this.grid.sortingExpressions.length && this.grid.sortingExpressions.indexOf(editableCell.column.field)) {
                     this.grid.cdr.detectChanges();
                 }