chore(*): Adding custom row selectors to roadmap

Author: kdinev

ROADMAP.md

@@ -9,6 +9,7 @@
 3. Fluent Theme [#5335](https://github.com/IgniteUI/igniteui-angular/issues/5335)
 4. Drag and Drop enhancements [#5319](https://github.com/IgniteUI/igniteui-angular/issues/5319)
 5. Multi-View Calendar + Range DatePicker [#4282](https://github.com/IgniteUI/igniteui-angular/issues/4282)
+5. Custom grid row selector templates [#4998](https://github.com/IgniteUI/igniteui-angular/issues/4998)
 
 ## Going down the road