doc: Drop proposed and unimplemented API doc

doc/ip-configuration-api.txt

@@ -1,47 +0,0 @@
-IP Configuration hierarchy
-===============================
-
-Service		net.connman.iwd
-Interface	net.connman.iwd.IPv4Configuration [Experimental]
-Interface	net.connman.iwd.IPv6Configuration [Experimental]
-Object path	/net/connman/iwd/{phy0,phy1,...}/{1,2,...}
-Object path	/net/connman/iwd/{phy0,phy1,...}/p2p_peers/{aa_bb_cc_dd_ee_ff}
-
-The interfaces net.connman.iwd.IPv4Configuration and
-net.connman.iwd.IPv6Configuration currently have the same sets of methods,
-signals and properties.  In station mode, when network configuration is
-enabled there may be one or both interfaces present on a device object in
-connected state depending on if IPv4 and IPv6 addresses have both been
-configured.  In P2P mode only net.connman.iwd.IPv4Configuration is used.
-
-Properties	string Method [readonly]
-
-			Indicates whether the local address was set
-			statically (value "static") or obtained automatically
-			such as through DHCP (value "auto").  Even when the
-			address was obtained from the remote end some
-			configuration bits, such as DNS addresses, may have
-			been overridden locally.
-
-		string Address [readonly]
-
-			Holds the local IP address.
-
-		byte PrefixLength [readonly]
-
-			Holds the prefix-length of the local subnet.  For
-			IPv4 this maps to the netmask.
-
-		string Gateway [readonly, optional]
-
-			Holds the gateway address for the subnet if one
-			exists.
-
-		array(string) DomainNameServers [readonly, optional]
-
-			Holds the list of domain name server addresses
-			configured if any.
-
-		array(string) DomainNames [readonly, optional]
-
-			Holds the network's local domain names if any exist.