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/commit_01.md

@@ -0,0 +1,20 @@
+## Git Commit 01
+
+### Objective
+
+Learn how to commit changes in Git repositories
+
+### Instructions
+
+1. Create a new directory
+2. Make it a git repository
+3. Create a new file called `file` with the content "hello commit"
+4. Commit your new file
+5. Run a git command to verify your commit was recorded
+
+### After you complete the exercise
+
+Answer the following:
+
+* What are the benefits of commits?
+* Is there another way to verify a commit was created?