Merge pull request #158 from unixorn/add-google-lessons-link

Add link to Lessons Learned from Twenty Years of Site Reliability Engineering

Author: unixorn

README.md

@@ -87,6 +87,7 @@ So you've got your first sysadmin/sre job or internship. Congratulations, it's g
 - [Git Magic (free ebook)](http://www-cs-students.stanford.edu/~blynn/gitmagic/) - `git` is a version control Swiss army knife. A reliable versatile multipurpose revision control tool whose extraordinary flexibility makes it tricky to learn, let alone master.
 - [Hello DNS](https://github.com/ahupowerdns/hello-dns) - Every sysadmin/sre needs to know how DNS works. Start with [DNS Basics](https://github.com/ahupowerdns/hello-dns/blob/master/basic.md) it's a good introduction.
 - [Lean Startup](https://smile.amazon.com/Lean-Startup-Entrepreneurs-Continuous-Innovation/dp/0307887898) or [Lean Enterprise](https://smile.amazon.com/Lean-Enterprise-Performance-Organizations-Innovate/dp/1449368425) - This pair describes the process surrounding implementation and use of Lean principles in Startup and Enterprise organizations. There are a number of companion pieces that extend the principles to specific fields of study and implementation, such as [Lean Analytics](https://smile.amazon.com/Lean-Analytics-Better-Startup-Faster/dp/1449335675).
+- [Lessons Learned from Twenty Years of Site Reliability Engineering](https://sre.google/resources/practices-and-processes/twenty-years-of-sre-lessons-learned/) - Google blog post about lessons learned over their first 20 years running data centers.
 - [LinkedIn's School of SRE](https://github.com/linkedin/school-of-sre) - Linkedin is using this curriculum for onboarding non-traditional hires and new college grads into the SRE role.
 - [The Missing Semester of Your CS Education](https://missing.csail.mit.edu/) - There’s one critical subject that’s rarely covered in CS programs, and is instead left to students to figure out on their own: proficiency with their tools. This course will teach you how to master the command-line, use a powerful text editor, use fancy features of version control systems, and much more!
 - [Site Reliability Engineering](http://shop.oreilly.com/product/0636920041528.do) - How Google Runs Production Systems. This can be read online for free at Google's [SRE site](https://landing.google.com/sre/book/index.html).