Update Tutorial 00 instructions with JupyterLab Git extension

[virdi]

We will use the pre-installed git extension in 2i2c JupyterLab for interacting with git/github. We need to update Tutorial 00 instructions with JupyterLab Git extension

[virdi]

Tutorial 00 now includes steps for using the git extension within the JupyterHub, including the steps to clone add commit and push using the graphical interface of the git extension.

We will track any further changes to Tutorial 00 in this issue.