ipld: add back missing intro resources

I'm not sure if these were intentionally left out of the copy/paste into
gitbook. Adding them back in just in case but they can be removed if that
was intentional.

docs/ipld/README.md

@@ -45,6 +45,21 @@ Only the smallest files in IPFS are stored as a single blob ("block"): to keep b
 
 Directories are graphs of named links pointing to files, forming graphs that address other graphs
 
+## Recommended Introductiory Resources
+
+[**ResNetLab: Course Module - Content Addressing**](https://research.protocol.ai/tutorials/resnetlab-on-tour/content-addressing/):
+
+{% embed url="https://www.youtube.com/watch?v=dN9EvujJ9cM" %}
+
+[**ResNetLab: Course Module - InterPlanetary Linked Data (IPLD)**](https://research.protocol.ai/tutorials/resnetlab-on-tour/ipld/)
+
+{% embed url="https://www.youtube.com/watch?v=Sgf6j_mCdjI" %}
+
+### Further Introductory Reading:
+
+* [**A Terse, Quick IPLD Primer for the Engineer**](https://ipld.io/docs/intro/primer/)
+* [**IPLD in the InterPlanetary Ecosystem**](https://ipld.io/docs/intro/ecosystem/)
+
 ## Sections | IPLD
 
 * [IPLD](README.md)