updated dns web tools

- signed-off-by: trimstray <trimstray@gmail.com>

README.md

@@ -192,6 +192,7 @@ for transferring data with URLs.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="http://viewdns.info/"><b>ViewDNS</b></a> - one source for free DNS related tools and information.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://dnslytics.com/"><b>DNSlytics</b></a> - online investigation tool.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://dnsspy.io/"><b>DNS Spy</b></a> - monitor, validate and verify your DNS configurations.<br>
+&nbsp;&nbsp;:small_orange_diamond: <a href="https://findsubdomains.com/"><b>Find subdomains online</b></a> - find subdomains for security assessment penetration test.<br>
 </p>
 
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