Detailed instructions for handling an exam review

Exam reviews have been chaos in the past. We should write up detailed instructions on how to do the exam review, including handling of emails, coordinating with the e-learning staff, etc.

This will require coordination with the users of the system (namely @hbrosen and @cdamm1).

added Needs specification label

changed milestone to %Korrekturtermin SoSe19

@cdamm1 asked for documentation of compatible formats for the example solution. We should write some documentation for importing where we can also specify which formats (e.g. asciimath, html, etc.) are allowed for the example solution.