cdceem.4: Clean description for apropos, tag spdx

CDCEEM is already defined in the document name, no need to list it in
parentheticals a second time in the document description. This brings
the apropos listing down to one line on the one true standard console.

MFC after: 3 days

(cherry picked from commit 89bc43a1ea9b23cac9cb94f0b684d5655c9a90e4)