Remove "Top Ten Git Terms" section.

Going to move this to a different location.
Create file for git terminology/lingo intro.
Rename lesson-2 to lesson-2.md
Add lesson overview paragraph and disclaimer.
Rename lesson-1(gitting-ready).md to lesson-1.md
Update and rename lesson-3.md to lesson-4.md
Rename lesson-2(team-development-101).md to lesson-3.md
Update lesson-3.md
Update README.md
Merge pull request #12 from notre-dame/moving-content-around

Moving content around