[zh] Fix typo in 01-chapter1

Change 丰富的 git 知识 --> 丰富的 Git 知识
In the original en-document, it should be Git rather than git.
What's more, this book often use Git rather than git when refer
to Git, so I think it should be a typo.
Merge pull request #789 from lord63/master

[zh] Fix typo in 01-chapter1