NetworkInterfaceSetConfiguration documentation change #309

In reference to: https://agsh.github.io/onvif/Cam_.html#~NetworkInterfaceSetConfiguration

Based on the library's code:

• enabled key is always required.
• enabled, manual, DHCP are always required while setting IPv4

As per onvif, these are optional but the implementation in this library requires these params. It would be great if the documentation was updated to show that these are not optional params.