Updated README.md (Toil Link, line56)

Updated a link on line 56, as it's a dead link to a deleted medium post.
From
[Toil: A Word Every Engineer Should Know](https://medium.com/production-ready/toil-a-word-every-engineer-should-know-f0b676e41c86)

To
[Toil: A Word Every Engineer Should Know](https://sharpend.io/toil-a-word-every-engineer-should-know/)

README.md

@@ -53,7 +53,7 @@ Contributions are always welcome!
 * [SRE: An incomplete guide to cultural Narnia](https://web.archive.org/web/20180820235243/http://anthonycaiafa.com/2016/04/10/sre-cultural-narnia/) - [[Video]](https://www.youtube.com/watch?v=__wypEhdcrQ&t=0s)
 * [Putting Together Great SRE Teams](https://www.usenix.org/conference/srecon16/program/presentation/krishnan)
 * [Work at Google: Meet our Production Engineers for Site Reliability Hangout on Air](https://www.youtube.com/watch?v=bwt6TZjefGM)
-* [Toil: A Word Every Engineer Should Know](https://medium.com/production-ready/toil-a-word-every-engineer-should-know-f0b676e41c86)
+* [Toil: A Word Every Engineer Should Know](https://sharpend.io/toil-a-word-every-engineer-should-know/)
 * [Engineering Reliability into Web Sites: Google SRE](https://research.google.com/pubs/pub32583.html)
 * [DEVOPS & SRE AMA - Building High Performance Organizations](http://pages.catchpoint.com/DEVOPS-SRE-AMA-mkty.html)
 * [John Allspaw's AMA on Incident Analysis and Postmortems](https://community.atlassian.com/t5/Jira-Ops-questions/I-m-John-Allspaw-Ask-Me-Anything-about-incident-analysis-and/qaq-p/957084)