Document IPv6Exit in the sample torrcs

Sample config-only change.

Implements 24703.

src/config/torrc.minimal.in-staging

@@ -163,6 +163,10 @@
 ## break its concealability and potentially reveal its IP/TCP address.
 #MyFamily $keyid,$keyid,...
 
+## Uncomment this if you want your relay to allow IPv6 exit traffic.
+## (Relays only allow IPv4 exit traffic by default.)
+#IPv6Exit 1
+
 ## A comma-separated list of exit policies. They're considered first
 ## to last, and the first match wins.
 ##

src/config/torrc.sample.in

@@ -163,6 +163,14 @@
 ## break its concealability and potentially reveal its IP/TCP address.
 #MyFamily $keyid,$keyid,...
 
+## Uncomment this if you do *not* want your relay to allow any exit traffic.
+## (Relays allow exit traffic by default.)
+#ExitRelay 0
+
+## Uncomment this if you want your relay to allow IPv6 exit traffic.
+## (Relays only allow IPv4 exit traffic by default.)
+#IPv6Exit 1
+
 ## A comma-separated list of exit policies. They're considered first
 ## to last, and the first match wins.
 ##