Add multiple-choice and grading improvements post

This MR adds a new post about the multiple-choice questions and grading improvements. It describes:

• Multiple-choice questions
• Anonymous grading mode
• Automatic grading
• Shuffling submissions

source/_posts/multiple-choice.md

@@ -14,5 +14,4 @@ Secondly, to make grading fairer, there is now an anonymous grading mode. When t
 
 Furthermore, Zesje is now able to grade blanks answers and multiple-choice questions for you. By default, Zesje marks the appropriate feedback options and you have to approve them yourself. With auto-approve, there is also the possibility to choose some cases for which you want Zesje to grade and approve answers automatically.
 
-<!-- TODO Information about shuffling submissions. -->
-Finally, ...
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+Finally, we have shuffled the submissions for each grader individually. This will limit the amount of collisions when grading the same question with a larger team, while still ensuring a deterministic ordering.
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