move the listing from docker to database

README.md

@@ -134,6 +134,7 @@ It's a great way to learn.
 * [**Python**: _DBDB: Dog Bed Database_](http://aosabook.org/en/500L/dbdb-dog-bed-database.html)
 * [**Python**: _Write your own miniature Redis with Python_](http://charlesleifer.com/blog/building-a-simple-redis-server-with-python/)
 * [**C++**: _Build Your Own Redis from Scratch_](https://build-your-own.org/redis)
+* [**Ruby**: _Build your own fast, persistent KV store in Ruby_](https://dinesh.wiki/posts/build-your-own-persistent-kv-store/)
 
 #### Build your own `Docker`
 
@@ -143,7 +144,6 @@ It's a great way to learn.
 * [**Python**: _A workshop on Linux containers: Rebuild Docker from Scratch_](https://github.com/Fewbytes/rubber-docker)
 * [**Python**: _A proof-of-concept imitation of Docker, written in 100% Python_](https://github.com/tonybaloney/mocker)
 * [**Shell**: _Docker implemented in around 100 lines of bash_](https://github.com/p8952/bocker)
-* [**Ruby**: _Build your own fast, persistent KV store in Ruby_](https://dinesh.wiki/posts/build-your-own-persistent-kv-store/)
 
 #### Build your own `Emulator / Virtual Machine`