docs: tproxy: fix formatting for nft code block

[ Upstream commit 149a133 ]

The nft command snippet for redirecting traffic isn't formatted
in a literal code block like the rest of snippets.
Fix the formatting inconsistency.

Signed-off-by: Chen Linxuan <chenlinxuan@uniontech.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
[ Backport from v6.16 ]
Signed-off-by: WangYuli <wangyuli@uniontech.com>

Author: black-desk

Documentation/networking/tproxy.rst

@@ -69,9 +69,9 @@ add rules like this to the iptables ruleset above::
     # iptables -t mangle -A PREROUTING -p tcp --dport 80 -j TPROXY \
       --tproxy-mark 0x1/0x1 --on-port 50080
 
-Or the following rule to nft:
+Or the following rule to nft::
 
-# nft add rule filter divert tcp dport 80 tproxy to :50080 meta mark set 1 accept
+    # nft add rule filter divert tcp dport 80 tproxy to :50080 meta mark set 1 accept
 
 Note that for this to work you'll have to modify the proxy to enable (SOL_IP,
 IP_TRANSPARENT) for the listening socket.