ipv6 -> IPv6

Co-authored-by: Catherine <whitequark@whitequark.org>

Author: Easyoakland

src/iface/interface/mod.rs

@@ -1302,7 +1302,7 @@ impl InterfaceInner {
             IpRepr::Ipv6(_) => {
                 // Check if we need to fragment it.
                 if total_ip_len > self.caps.ip_mtu() {
-                    net_debug!("ipv6 fragmentation support is unimplemented. Dropping.");
+                    net_debug!("IPv6 fragmentation support is unimplemented. Dropping.");
                     Ok(())
                 } else {
                     tx_token.consume(total_len, |mut tx_buffer| {