Remove setting default editor from episode 2

[michaelberks]

This change addresses #847 and recommends removing the section on setting Git's default editor from episode 2 of the lesson, with an additional small change in the initial bullet point list at the start of the lesson, replacing the reference to setting the editor with "choosing how we deal with line endings in text files". My reasoning for this change is give in my comment on the issue here.

I have checked the lesson still compiles and formats correctly by rebuilding and running on a local server.

This PR has been made as a contribution towards instructor training.