man: set private key in PreUp rather than PostUp

This is probably more sensible, since there's no point in letting
traffic flow before the interface is configured.

Signed-off-by: Jason A. Donenfeld <[email protected]>

Author: zx2c4

Diff for: src/man/wg-quick.8

@@ -168,7 +168,7 @@ sockets, which bypass Netfilter.) When IPv6 is in use, additional similar lines
 Or, perhaps it is desirable to store private keys in encrypted form, such as through use of
 .BR pass (1):
 
-    \fBPostUp = wg set %i private-key <(pass WireGuard/private-keys/%i)\fP
+    \fBPreUp = wg set %i private-key <(pass WireGuard/private-keys/%i)\fP
 .br
 
 For use on a server, the following is a more complicated example involving multiple peers: