docs(table): fix typo in MatRowDef description (#13170)

Author: tplk

src/lib/table/row.ts

@@ -49,7 +49,7 @@ export class MatFooterRowDef extends _CdkFooterRowDef {}
 
 /**
  * Data row definition for the mat-table.
- * Captures the footer row's template and other footer properties such as the columns to display and
+ * Captures the data row's template and other properties such as the columns to display and
  * a when predicate that describes when this row should be used.
  */
 @Directive({