Update doc/sphinx/arm/dhcp4-srv.rst, doc/sphinx/arm/dhcp6-srv.rst,...
[#2569 (closed)] A couple of minor typos in the ARM Update doc/sphinx/arm/dhcp4-srv.rst, doc/sphinx/arm/dhcp6-srv.rst, doc/sphinx/arm/hooks-ddns-tuning.rst, doc/sphinx/arm/hooks.rst
Edited by Peter Davies