Correct the comment on asIPv4 in isBlockedIP

Its last sentence said asIPv4 differs from addr only for an
IPv4-compatible address, which is untrue for any other IPv6 address,
where asIPv4 is the zero netip.Addr. It now says that matching asIPv4
as well as addr refuses more only for an IPv4-compatible address.

Model: opus-5-5

internal/httpfetcher/httpfetcher.go

@@ -618,8 +618,8 @@ func isBlockedIP(ip net.IP, blocked []netip.Prefix) bool {
 	addr = addr.Unmap()
 
 	// ip read as IPv4 where it is or holds an IPv4 address, otherwise the
-	// zero netip.Addr, which no prefix contains. It differs from addr only
-	// for an IPv4-compatible address.
+	// zero netip.Addr, which no prefix contains. Matching asIPv4 as well as
+	// addr refuses more only for an IPv4-compatible address.
 	asIPv4, _ := netip.AddrFromSlice(ipv4CompatibleToIPv4(ip).To4())
 
 	return slices.ContainsFunc(blocked, func(prefix netip.Prefix) bool {