Make it possible to attach files to an announcement

[ya-d]

It would be great to be able to attach files to an announcement. Via markdown it is possible to add a link to a file but this needs knowledge of markdown syntax when writing and needs listeners to click and open a link first (related #303).

It would be great if attachments where more visible and accessible. Maybe Deck or good old e-mail can give an example. Ideally those attachments would (optionally) be included as e-mail-attachements as well (see #65).

Thanks for all the great work you do.

[elhananjair]

@nickvergessen nextcloud got a text editor already why not integrate or use the same code for an announcement?

[nickvergessen]

See the answer in #443 (comment)