Updated items in branching section on main README.md

README.md

@@ -31,11 +31,10 @@ Training material for the Git for Beginners ABiMS training session
   1. Propagating changes to the remote repository
   1. Keeping a local repository synchronized with a remote repository
 
-### Branching Basics
-  1. Default branches
-  1. Creating new branches
-  1. Switching between branches
-  1. Merging branches
+### [Branching Basics](./04-branching-basics/README.md)
+  1. Rationale for using branches
+  1. Using GitLab to manage branches
+  1. Using the CLI to manage branches
 
 ### Team collaboration
   1. Project roles in GitLab