Hang in there ... Flarum is still beta, so it's bound to be missing a few features you want.
If you like, you could create a new thread under the Features tag and request this feature. (I don't recall anyone asking for an Impressum page before now.) Be sure to add specific information about the sort of content you might want on the page, how the page would work (in terms of sharing content etc.) within the Flarum site as a whole, and anything else you can think of that will help people get a better idea of what you're looking for.
Even if that feature isn't eventually included in Flarum, your request may inspire some intrepid programmer to create exactly the extension you need.
