Create card with a link to our documentation to help teachers get started

[jorg-vr]

This pull request adds a card to the homepage that links to our documentation.

This card is visible for all teachers who are not admin of any course.

It is also visible for students who are the only members of their institution, as we assume the first users of an institution to most likely be teachers.

As said this card remains as long as the teacher is not administering any courses

I'll make use of this occasion to update the linked documentation:

• Documentation update can be found at Update getting started screenshots dodona-edu.github.io#400

Closes #3433

[bmesuere]

I did a few suggestions to improve the phrasing.

Do we have a way to make it stand out more? Since it is a static and temporary message, maybe use a colored card?

[jorg-vr]

Ik heb het nu secondary color gegeven, waardoor het echt opvalt

Ook gekleurd maar iets minder opvallend met info kleur:

Zeg maar wat je voorkeur is

[dodona-server]

I like the colored ones over the white one. I have a slight preference for pink because blue looks a lot like the course cards.

What do we think of the position? I would maybe move it down to the bottom of the sidebar to make it a bit less prominent. New users will not have a lot of content in the sidebar so it will still be shown above the fold. (The reason for this is that we might have legitimate users that are alone in their institution, but not a teacher. E.g., user signing in with their company account. They probably don't want teacher rights and in that case an unremovable card on the top of the sidebar might be a bit too much.)

What do @chvp and @niknetniko think about position and color?

[bmesuere]

Woops, wrong account :)

[chvp]

I like the pink more than the info colour. I don't have a strong opinion about the position, users who are alone in their institution are probably unlikely to have a crowded sidebar.