Support SecureDrop Workstation release announcement blog posts

[rocodes]

Dear web team!

As we move closer to SDW leaving pilot phase and entering more official phase, it would be great to be able to make SDW related release announcements on Wagtail, for both releases in securedrop-client and securedrop-workstation. (I mention the repos because I know there is some logic on the securedrop side that validates a release announcement against a tagged release object).

We have not discussed this as a team, but at the moment we don't need both pre-release and release announcements, just release announcements. That could change depending on team wishes.

Just filing here to start the discussion both for long-term, as well as in advance of our next release freedomofpress/securedrop-client#1867

Thank you!

[rocodes]

Update: we published https://securedrop.org/news/securedrop-client-0_10_0-released/ yesterday thanks to @harrislapiroff mentioning that it should Just Work ™️ without associating a release object to the blog post - it was my misunderstanding that that field was mandatory and that the page validation wouldn't let you save a page without it, but that's not the case.

Down the line it would be useful to figure out if we do want to mimic the SecureDrop release posts where we indicate a version number (I think we might indeed want this) but since there are 2 components, Workstation and Client, it's probably a conversation, and the current way of doing it is a fine workaround.

Thanks and hope this explanation made sense.

[rocodes]

(Basically, this is low priority)