docs: add subsections for servos & steppers
docs: add subsections for servos & steppers

The AXIS_n section of the INI docs was a bit confusing.  It started
with generic ini variables applicable to all axis configs, then had a
subsection for homing.  In the homing section it then continued with
ini variables for servos and steppers.  This was confusing.

This commit adds a subsection for Servos and one for Steppers, after
the Homing subsection.  Hopefully this will be clearer.

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