gh-156680 - Update IPv4Network and IPv6Network docstring.

Mention that the address argument can be a two-tuple representing
address description and a netmask.

Author: orsenthil

Lib/ipaddress.py

@@ -1567,6 +1567,13 @@ def __init__(self, address, strict=True):
               IPv4Interface(int(IPv4Interface('192.0.2.1'))) ==
                 IPv4Interface('192.0.2.1')
 
+              The address can also be a two-tuple of an address description
+              and a netmask, where the address description is either a
+              string, a 32-bits integer, a 4-bytes packed integer, or an
+              existing IPv4Address object; and the netmask is either an
+              integer representing the prefix length (e.g. 24) or a string
+              representing the prefix mask (e.g. '255.255.255.0').
+
         Raises:
             AddressValueError: If ipaddress isn't a valid IPv4 address.
             NetmaskValueError: If the netmask isn't valid for
@@ -2358,6 +2365,12 @@ def __init__(self, address, strict=True):
               IPv6Network(int(IPv6Network('2001:db8::'))) ==
                 IPv6Network('2001:db8::')
 
+              The address can also be a two-tuple of an address description
+              and a netmask, where the address description is either a
+              string, a 128-bits integer, a 16-bytes packed integer, or an
+              existing IPv6Address object; and the netmask is an integer
+              representing the prefix length.
+
             strict: A boolean. If true, ensure that we have been passed
               A true network address, eg, 2001:db8::1000/124 and not an
               IP address on a network, eg, 2001:db8::1/124.