/usr/share/doc/ is in drush 4.5-6.
This file is owned by root:root, with mode 0o755.
..
/usr/share/doc/drush/changelog.Debian.gz
/usr/share/doc-base/drush
/usr/share/doc/drush/
/usr/share/doc/drush/examples/
/usr/share/doc/drush/examples/example.drushrc.php
/usr/share/doc/drush/examples/sandwich.txt
/usr/share/doc/drush/examples/helloworld.script
/usr/share/doc/drush/examples/example.aliases.drushrc.php
/usr/share/doc/drush/examples/sandwich.drush.inc
/usr/share/doc/drush/examples/example.bashrc
/usr/share/doc/drush/examples/example.drush.ini
/usr/share/doc/drush/examples/policy.drush.inc
/usr/share/doc/drush/examples/xkcd.drush.inc
/usr/share/doc/drush/examples/sandwich-topic.txt
/usr/share/doc/drush/README.txt
/usr/share/doc/drush/copyright
/usr/share/doc/drush/docs/
/usr/share/doc/drush/docs/upgrade.html
/usr/share/doc/drush/docs/bootstrap.html
/usr/share/doc/drush/docs/shellscripts.html
/usr/share/doc/drush/docs/drush.api.php
/usr/share/doc/drush/docs/context.html
/usr/share/doc/drush/docs/commands.html
/usr/share/doc/drush/docs/index.html