Wiki and Material section: Display date of publication, not date of last update

[shavek]

We noticed that in the Wiki and Material section, at the top of each entry the date of last update is displayed, but rather we would like the date of publication shown here, which we can edit in the "edit" section of each entry.

So this is how it looks now:

But we want the date of publication be shown, which we can edit in the backend:

[benjaoming]

This is easy to fix, but would you like this field to be automatically maintained or manual?

[benjaoming]

Ah, I misunderstood the original issue: Will make it so there's a clear field that you can manage manually.

Notice that this contradicts having an automatic field. Now you have to update it manually.

I'll change the text to say "Published: ..." since that's easier to maintain.