updated 'Net-tools'

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

README.md

@@ -142,6 +142,7 @@ for transferring data with URLs.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="http://ping.eu/"><b>Ping.eu</b></a> - online Ping, Traceroute, DNS lookup, WHOIS and others.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://network-tools.com/"><b>Network-Tools</b></a> - network tools for webmasters, IT technicians & geeks.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://www.url-encode-decode.com/"><b>URL Encode/Decode</b></a> - tool from above to either encode or decode a string of text.<br>
+&nbsp;&nbsp;:small_orange_diamond: <a href="https://regexr.com/"><b>RegExr</b></a> - online tool to learn, build, & test Regular Expressions (RegEx / RegExp).<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://www.hardenize.com/"><b>Hardenize</b></a> - deploy the security standards.<br>
 </p>