doc: updated links

docs/md/links.md

@@ -132,6 +132,7 @@ I hope this list can grow much more in the future:
     - [Camera Component UI](https://www.youtube.com/watch?v=RIMt_6agUiU).
     - [Drawing Component UI](https://www.youtube.com/watch?v=u3yq8s3KuSE).
     - [Transform Component UI](https://www.youtube.com/watch?v=8JqcXYbzPJc).
+    - [Adding/Removing Entities and Components UI](https://www.youtube.com/watch?v=PsyGmsIgp9M).
   * [Ability Creator](https://www.erichildebrand.net/blog/ability-creator-project-retrospect):
     project retrospect by [Eric Hildebrand](https://www.erichildebrand.net/).