Exercises with vscode, say how to use vscode commandline where that is the recommended method

[rkdarst]

For example "line-by-line" commits, it says we recommend to use the command line. We can say how to open the terminal in VSCode and how it starts the terminal in the right directory.

[rantahar]

If "line-by-line" means committing only certain lines in a modified file, I think we should recommend using the VSCode interface. Mainly saying this because it's what I use and I think the interface is better than in the terminal.