adding a video about how to create a PR

Author: mariana-caldas

README.md

@@ -22,6 +22,7 @@ This is a video that explains a little bit how to start collaborating with the p
 These are the videos that explain in detail how to branch out and submit PR:
 
 [Branching out from an up to date master](https://www.loom.com/share/77c3bea45d86428a86c897ac3ccaacc4)
+[Creating the PR with the first commit](https://www.loom.com/share/04e326b873db4af7a4ce86c74183d554)
 
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