Attachment Page Content is a confusing label

[batmoo]

On the Edit Media screen, the "Description" field is renamed to "Attachment Page Content". It's a bit confusing to have the field label changed to something so drastically different (took me a while to figure out what that field was too :)).

I'd recommend either updating the label to something like "Attachment Content (Description)" so there's a hint that this is the field-formerly-known-as-description (then, drop the parenthesis in 3.6 once users are more familiarized with it.)

I'd be down with a hint that it's "the field-formerly-known-as-description".

I could go for "(Description)" in parentheses. But "Attachment Content" doesn't make much sense. The content of an attachment is probably the media item itself.

I could also just go for going back to Description. When it is outside of the media modal, it is much less of a problem to have these four fields.

Gonna just handle this in #22759.