pf.conf.5: additional quoting for ranges in lists

When defining network address ranges in macros that will later be used
as items in list macro, these ranges must be quoted with additiona
simple quotes.

For instance, the following does not work and is rejected as a syntax
error:

    usr = "192.168.1.0/24"
    srv = "192.168.2.10 - 192.168.29"
    nat_ranges = "{" $usr $srv "}"

Defining ranges as the following instead will work:
    usr = "'192.168.1.0/24'"
    srv = "'192.168.2.10 - 192.168.29'"

MFC after: 3 days
Reviewed by: Alexander Ziaee <concussious@runbox.com>

share/man/man5/pf.conf.5

@@ -100,13 +100,20 @@ Macro names may not be reserved words (for example
 .Ar in ,
 .Ar out ) .
 Macros are not expanded inside quotes.
+Ranges of network addresses used in macros that will be expanded in lists
+later on must be quoted with additional simple quotes.
 .Pp
 For example,
 .Bd -literal -offset indent
 ext_if = \&"kue0\&"
 all_ifs = \&"{\&" $ext_if lo0 \&"}\&"
 pass out on $ext_if from any to any
 pass in  on $ext_if proto tcp from any to any port 25
+
+usr_lan_range = "'192.0.2.0/24'"
+srv_lan_range = "'198.51.100.0 - 198.51.100.255'"
+nat_ranges = \&"{\&" $usr_lan_range $srv_lan_range \&"}\&"
+nat on $ext_if from $nat_ranges to any -> ($ext_if)
 .Ed
 .Sh TABLES
 Tables are named structures which can hold a collection of addresses and