Last modified: 2012-05-21 18:00:44 UTC
https://gerrit.wikimedia.org/r/#/c/8331/ tried to do this, but half-assed :). The intro sentence should be: "This is an overview of the interwiki table. [Show/Hide legend]", where "[Show/Hide legend]" should be a visible link that expands or collapses the table.
Completed spec in https://gerrit.wikimedia.org/r/#/c/8331/.