It appears that when adding any new license, one needs to send a
notice to gentoo-dev. I have added CCPL-Attribution-2.5 (see
attachment or http://creativecommons.org/licenses/by/2.5/legalcode)
and added it to the FREE-DOCUMENTS license group (same as
CCPL-Attribution-3.0, acked by Robin Jonson)*. The license is required
for some files that are part of a package that I am adding to the tree
Since CCPL-Attribution-2.5 is an obviously free documentation license,
and since CCPL-Attribution-2.0 and 3.0 and
CCPL-Attribution-ShareAlike-2.5 are already in licenses/, I assume
that this addition is uncontroversial.
[*] FREE-DOCUMENTS and not FSF-APPROVED-OTHER because the only version
of CCPL-Attribution that is explicitly listed as approved by the FSF
is 2.0 (see http://www.gnu.org/licenses/license-list.html).