Fix some ipaddress documentation errors (GH-6021)


* fix a typo: documention -> documentation
* fix the type of IPv?Network.hostmask
* add documentation about IPv?Network.netmask
* fix IPv6Network constructor doc that extended netmasks are not supported
(cherry picked from commit e405096ea91f516d411095b6fea4eec9668eac88)

Co-authored-by: Xiang Zhang <angwerzx@126.com>
1 file changed