docs(material/table): Correct checkbox label on select all checkbox (#22748)

Change the label on the "select all" checkbox to read "deselect" and "select" correctly

Author: dbosh88

src/components-examples/material/table/table-selection/table-selection-example.ts

@@ -55,7 +55,7 @@ export class TableSelectionExample {
   /** The label for the checkbox on the passed row */
   checkboxLabel(row?: PeriodicElement): string {
     if (!row) {
-      return `${this.isAllSelected() ? 'select' : 'deselect'} all`;
+      return `${this.isAllSelected() ? 'deselect' : 'select'} all`;
     }
     return `${this.selection.isSelected(row) ? 'deselect' : 'select'} row ${row.position + 1}`;
   }