Modify the structure of README.md

Instead of having exercises in their own separate section,
they are now part of the main topics sections.

This should make the learning process easier to follow
where users have both exercises and questions in the same
place.

In addition, added a couple of new questions & exercises
and modified existing scripts accordingly.

exercises/git/branch_01.md

@@ -0,0 +1,19 @@
+## Git Commit 01
+
+### Objective
+
+Learn how to work with Git Branches
+
+### Instructions
+
+1. Pick up a Git repository (or create a new one) with at least one commit
+2. Create a new branch called "dev"
+3. Modify one of the files in the repository
+4. Create a new commit
+5. Verify the commit you created is only in "dev" branch
+
+### After you complete the exercise
+
+Answer the following:
+
+1. Why branches are useful? Give an example of one real-world scenario for using branches