spec-revs: Remove nonexistent systemtray 0.4
The revisions for the systemtray spec included a version 0.4
which was pointed at revision HEAD
. However,
- The index already includes a "latest version" link
- The spec has not changed since version 0.3, and in fact still lists "0.3" as the version even in the HEAD rev.
This confusingly creates the incorrect impression that there's a version 0.4 of the spec, which does not exist.