docs(material/table): fix description for MatHeaderRow (#27154)

(cherry picked from commit 4533583)

Author: nishchay7pixels

src/material/table/row.ts

@@ -52,7 +52,7 @@ export class MatFooterRowDef extends CdkFooterRowDef {}
 })
 export class MatRowDef<T> extends CdkRowDef<T> {}
 
-/** Footer template container that contains the cell outlet. Adds the right class and role. */
+/** Header template container that contains the cell outlet. Adds the right class and role. */
 @Component({
   selector: 'mat-header-row, tr[mat-header-row]',
   template: CDK_ROW_TEMPLATE,