fix: typo in iptables version to install firewall RC

Author: mazzma12

crowdsec-docs/unversioned/bouncers/firewall.mdx

@@ -47,7 +47,7 @@ Packages for crowdsec-firewall-bouncer [are available on our repositories](/docs
 To know if your system is using iptables or nftables, you can run the following command:
 
 iptables -V
-If you see the mention of 'nt_tables' in the output, you are using nftables.
+If you see the mention of 'nf_tables' in the output, you are using nftables.
 :::
 
 ### IPTables