net: allow parameters to a single address config

In the case of a single line of configuration, where the address has
parameters, the parameters were being treated as seperate addresses.
Eg:
config_eth0="4321:0:1:2:3:4:567:89ab/64 nodad home preferred_lft 0"

Also document usage of parameters in the net example, and note that
multiple addresses on a single line cannot be mixed with parameters.
Newlines are required to seperate the addresses.

X-Gentoo-Bug: 398827
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=398827

Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>

doc/net.example.Linux.in

@@ -68,6 +68,7 @@
 # NOTE: ifconfig creates an aliased device for each extra IPv4 address
 #       (eth0:1, eth0:2, etc)
 #       iproute2 does not do this as there is no need to
+# WARNING: You cannot mix multiple addresses on a line with other parameters!
 #config_eth0="192.168.0.2/24 192.168.0.3/24 192.168.0.4/24"
 # However, that only works with CIDR addresses, so you can't use netmask.
 
@@ -85,6 +86,14 @@
 # If you don't want ANY address (only useful when calling for advanced stuff)
 #config_eth0="null"
 
+# If you need to pass parameters to go with an address, you can do so on the
+# same line as the address. You should split multiple addresses with newlines.
+# WARNING: You cannot mix multiple addresses on a line with other parameters!
+#config_eth0="192.168.0.2/24 scope host"
+#config_eth0="4321:0:1:2:3:4:567:89ab/64 nodad home preferred_lft 0"
+#config_eth0="192.168.0.2/24 scope host
+#4321:0:1:2:3:4:567:89ab/64 nodad home preferred_lft 0"
+
 # Here's how to do routing if you need it
 # We add an IPv4 default route, IPv4 subnet route and an IPv6 unicast route
 #routes_eth0="default via 192.168.0.1