added 'hey'

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

README.md

@@ -171,6 +171,7 @@ Only main chapters:
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://github.com/wg/wrk"><b>wrk</b></a> - is a modern HTTP benchmarking tool capable of generating significant load.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://github.com/codesenberg/bombardier"><b>bombardier</b></a> - fast cross-platform HTTP benchmarking tool written in Go.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://github.com/cmpxchg16/gobench"><b>gobench</b></a> - http/https load testing and benchmarking tool.<br>
+&nbsp;&nbsp;:small_orange_diamond: <a href="https://github.com/rakyll/hey"><b>hey</b></a> - HTTP load generator, ApacheBench (ab) replacement, formerly known as rakyll/boom.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://github.com/OJ/gobuster"><b>gobuster</b></a> - free and open source directory/file & DNS busting tool written in Go.<br>
 </p>