Fix html doc building error introduced in 30341a8
Fix html doc building error introduced in 30341a8

I don't know how the "smart quote" apostrophes got written in
the LyX file but conversion back to version 221 (the version
understood by lxtree which builds html documentation) turns this
into an ERT which makes the html docs fail to build.  Replaced
with a dumb apostrophe, all seems well.

EqAfrica/machinekit,cdsteinkuehler/linuxcnc,Cid427/machinekit,ianmcmahon/linuxcnc-mirror,mhaberler/machinekit,kinsamanka/machinekit,unseenlaser/linuxcnc,jaguarcat79/ILC-with-LinuxCNC,ArcEye/machinekit-testing,Cid427/machinekit,Cid427/machinekit,ArcEye/MK-Qt5,kinsamanka/machinekit,RunningLight/machinekit,aschiffler/linuxcnc,RunningLight/machinekit,narogon/linuxcnc,cdsteinkuehler/linuxcnc,strahlex/machinekit,EqAfrica/machinekit,mhaberler/machinekit,araisrobo/linuxcnc,ianmcmahon/linuxcnc-mirror,narogon/linuxcnc,ikcalB/linuxcnc-mirror,jaguarcat79/ILC-with-LinuxCNC,ArcEye/MK-Qt5,bmwiedemann/linuxcnc-mirror,bobvanderlinden/machinekit,bobvanderlinden/machinekit,EqAfrica/machinekit,strahlex/machinekit,RunningLight/machinekit,strahlex/machinekit,kinsamanka/machinekit,mhaberler/machinekit,RunningLight/machinekit,EqAfrica/machinekit,cnc-club/linuxcnc,jaguarcat79/ILC-with-LinuxCNC,bmwiedemann/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,Cid427/machinekit,ianmcmahon/linuxcnc-mirror,ikcalB/linuxcnc-mirror,cdsteinkuehler/MachineKit,cdsteinkuehler/MachineKit,aschiffler/linuxcnc,ArcEye/MK-Qt5,unseenlaser/machinekit,kinsamanka/machinekit,araisrobo/linuxcnc,ianmcmahon/linuxcnc-mirror,ikcalB/linuxcnc-mirror,cnc-club/linuxcnc,mhaberler/machinekit,araisrobo/machinekit,jaguarcat79/ILC-with-LinuxCNC,strahlex/machinekit,cdsteinkuehler/MachineKit,araisrobo/linuxcnc,araisrobo/machinekit,mhaberler/machinekit,araisrobo/machinekit,cdsteinkuehler/linuxcnc,unseenlaser/machinekit,cnc-club/linuxcnc,unseenlaser/machinekit,mhaberler/machinekit,bmwiedemann/linuxcnc-mirror,araisrobo/machinekit,narogon/linuxcnc,unseenlaser/machinekit,araisrobo/machinekit,ArcEye/MK-Qt5,ianmcmahon/linuxcnc-mirror,araisrobo/machinekit,Cid427/machinekit,ArcEye/machinekit-testing,Cid427/machinekit,cdsteinkuehler/linuxcnc,bobvanderlinden/machinekit,cdsteinkuehler/MachineKit,bobvanderlinden/machinekit,kinsamanka/machinekit,araisrobo/machinekit,cnc-club/linuxcnc,narogon/linuxcnc,strahlex/machinekit,kinsamanka/machinekit,cnc-club/linuxcnc,cnc-club/linuxcnc,RunningLight/machinekit,kinsamanka/machinekit,bmwiedemann/linuxcnc-mirror,araisrobo/machinekit,ArcEye/machinekit-testing,narogon/linuxcnc,unseenlaser/linuxcnc,ArcEye/machinekit-testing,ArcEye/MK-Qt5,bobvanderlinden/machinekit,ArcEye/machinekit-testing,strahlex/machinekit,Cid427/machinekit,bobvanderlinden/machinekit,cnc-club/linuxcnc,unseenlaser/machinekit,cdsteinkuehler/linuxcnc,aschiffler/linuxcnc,araisrobo/linuxcnc,aschiffler/linuxcnc,EqAfrica/machinekit,araisrobo/machinekit,ArcEye/machinekit-testing,EqAfrica/machinekit,ianmcmahon/linuxcnc-mirror,unseenlaser/linuxcnc,mhaberler/machinekit,bmwiedemann/linuxcnc-mirror,jaguarcat79/ILC-with-LinuxCNC,ikcalB/linuxcnc-mirror,unseenlaser/linuxcnc,unseenlaser/linuxcnc,ArcEye/MK-Qt5,ikcalB/linuxcnc-mirror,mhaberler/machinekit,ianmcmahon/linuxcnc-mirror,RunningLight/machinekit,RunningLight/machinekit,cdsteinkuehler/MachineKit,aschiffler/linuxcnc,bobvanderlinden/machinekit,unseenlaser/machinekit,unseenlaser/machinekit,ikcalB/linuxcnc-mirror,ArcEye/machinekit-testing,cdsteinkuehler/linuxcnc,ArcEye/MK-Qt5,Cid427/machinekit,bmwiedemann/linuxcnc-mirror,bobvanderlinden/machinekit,RunningLight/machinekit,ArcEye/machinekit-testing,cdsteinkuehler/MachineKit,EqAfrica/machinekit,ikcalB/linuxcnc-mirror,EqAfrica/machinekit,araisrobo/linuxcnc,strahlex/machinekit,ArcEye/MK-Qt5,unseenlaser/machinekit,kinsamanka/machinekit