Add links to external learning resources

doc/gitlab-basics/start-using-git.md

@@ -22,6 +22,11 @@ This guide will help you get started with Git through the command line and can b
 for Git commands in the future. If you're only looking for a quick reference of Git commands, you
 can download GitLab's [Git Cheat Sheet](https://about.gitlab.com/images/press/git-cheat-sheet.pdf).
 
+> For more information about the advantages of working with Git and GitLab:
+>
+> - Watch the [GitLab Source Code Management Walkthrough](https://www.youtube.com/watch?v=wTQ3aXJswtM) video.
+> - Learn how GitLab became the backbone of [Worldline](https://about.gitlab.com/customers/worldline/)’s development environment.
+
 TIP: **Tip:**
 To help you visualize what you're doing locally, there are
 [Git GUI apps](https://git-scm.com/download/gui/) you can install.

doc/topics/git/numerous_undo_possibilities_in_git/index.md

@@ -26,6 +26,11 @@ This means that until Git automatically cleans detached commits (which cannot be
 accessed by branch or tag) it will be possible to view them with `git reflog` command
 and access them with direct commit ID. Read more about _[redoing the undo](#redoing-the-undo)_ in the section below.
 
+> For more information about working with Git and GitLab:
+>
+> - Learn why [North Western Mutual chose GitLab](https://youtu.be/kPNMyxKRRoM) for their Enterprise source code management.
+> - Learn how to [get started with Git](https://about.gitlab.com/resources/whitepaper-moving-to-git/).
+
 ## Introduction
 
 This guide is organized depending on the [stage of development](https://git-scm.com/book/en/v2/Git-Basics-Recording-Changes-to-the-Repository)