Add TinkerPop

Added [awesome-tinkerpop](https://github.com/mohataher/awesome-tinkerpop) to databases section.

Closes #667

readme.md

@@ -311,6 +311,7 @@ Check out my [blog](https://blog.sindresorhus.com) and follow me on [Twitter](ht
 - [Doctrine](https://github.com/TomasVotruba/awesome-doctrine) - PHP ORM.
 - [MongoDB](https://github.com/ramnes/awesome-mongodb)
 - [RethinkDB](https://github.com/d3viant0ne/awesome-rethinkdb)
+- [TinkerPop](https://github.com/mohataher/awesome-tinkerpop) - Graph computing framework.
 
 
 ## Media