Correct spelling mistakes and add small improvements to problems in Chapter 2.
The renaming of the problems might make it more difficult to compare, but reviewnb works nicely https://github.com/martavp/pv-textbook/issues/6
@rubennj you can merge when you review this
Correct spelling mistakes and add small improvements to problems in Chapter 2. The renaming of the problems might make it more difficult to compare, but reviewnb works nicely https://github.com/martavp/pv-textbook/issues/6 @rubennj you can merge when you review this