Help users pick a series for a video uploaded

[oas777]

I know this is a problem of having too many

• courses with the same name recorded and
• too many recordings overall,

but I think it would be helpful generally to add a date/year and/or name to the list of series so users can select the correct one more easily. It's definitively more helpful than the description.

[LukasKalbertodt]

With #1373, this is already improved a lot I think:

However, playing around with it I thought of two things that could still be improved:

• Currently the results are sorted by updated date. But we show the created date, which might be confusing. I think this problem is made worse by our weird test data on our test deployment -> for most actual production deployments, "sort by updated" and "sort by created" probably result in almost the same order. But still: I think it might be more useful to order by created? Sure, if you just edited an old series and now want to add it to a page, you don't immediately see it. But I think that's fine.

• Currently, searching for the year does not bring up the series, because the created date is not searchable in our index. And we probably don't want to make the whole date string (in ISO format) searchable! But maybe extract the year into a separate search index field and make that searchable?