/usr/share/help/C/ is in lightdm 1.10.3-3.
This file is owned by root:root, with mode 0o755.
..
/usr/share/help/C/lightdm/
/usr/share/help/C/lightdm/autologin.page
/usr/share/help/C/lightdm/config.page
/usr/share/help/C/lightdm/default-greeter.page
/usr/share/help/C/lightdm/default-session.page
/usr/share/help/C/lightdm/diagnostics.page
/usr/share/help/C/lightdm/guest.page
/usr/share/help/C/lightdm/index.page
/usr/share/help/C/lightdm/legal.xml
/usr/share/help/C/lightdm/local-sessions.page
/usr/share/help/C/lightdm/remote-sessions.page
/usr/share/help/C/lightdm/seat.page
/usr/share/help/C/lightdm/standard-authentication.page
/usr/share/help/C/lightdm/user-list.page
/usr/share/help/C/lightdm/user-switching.page
/usr/share/help/C/lightdm/vnc.page
/usr/share/help/C/lightdm/write-greeter.page
/usr/share/help/C/lightdm/xdmcp.page