Add Building Regex Engine in Go tutorial

README.md

@@ -333,6 +333,7 @@ It's a great way to learn.
 
 * [**C**: _A Regular Expression Matcher_](https://www.cs.princeton.edu/courses/archive/spr09/cos333/beautiful.html)
 * [**C**: _Regular Expression Matching Can Be Simple And Fast_](https://swtch.com/~rsc/regexp/regexp1.html)
+* [**Go**: _How to build a regex engine from scratch_](https://rhaeguard.github.io/posts/regex)
 * [**JavaScript**: _Build a Regex Engine in Less than 40 Lines of Code_](https://nickdrane.com/build-your-own-regex/)
 * [**JavaScript**: _How to implement regular expressions in functional javascript using derivatives_](http://dpk.io/dregs/toydregs)
 * [**JavaScript**: _Implementing a Regular Expression Engine_](https://deniskyashif.com/2019/02/17/implementing-a-regular-expression-engine/)