Expand ipv6-subtrees manpage entry.

babeld.man

@@ -189,8 +189,14 @@ equivalent to the command-line option
 .BR \-r .
 .TP
 .BR ipv6-subtrees " {" true | false }
-This specifies whether to use native source-specific table rather than using
-multiple tables with rules.
+This specifies whether to use native source-specific IPv6 forwarding
+rather than multiple routing tables.  The default is
+.BR false ,
+setting this to
+.B true
+is recommended on sufficiently recent
+.I Linux
+kernels.
 .TP
 .BI debug " level"
 This specifies the debugging level, and is equivalent to the command-line