add youtube video of adding your first GitHub pull request

Author: Damon Maneice

collections/choosing-projects/index.md

@@ -5,6 +5,7 @@ items:
  - hoodiehq/hoodie
  - beeware/batavia
  - Homebrew/brew
+ - https://www.youtube.com/embed/dSl_qnWO104
 display_name: How to choose (and contribute to) your first open source project
 created_by: kytrinyx
 ---