[Chore] Add build status (#744)

Author: mirkoAlic

README.md

@@ -2,13 +2,18 @@
 
 Ethereum-like Blockchain Scala client built by IOHK's Team Grothendieck.
 
-### Status
+### Status - Release
 
-Continuous Integration Build Status [FIXME]
+For continuous integration we're using:
+- [Buildkite](https://buildkite.com/input-output-hk/mantis) to run all the Scala build steps [![Build status](https://badge.buildkite.com/8a284e6f0af90afa544e06c8136b519f9f287f005ca581d8ed.svg?branch=master&theme=github)](https://buildkite.com/input-output-hk/mantis)
+- [Hydra](https://hydra.project42.iohkdev.io/project/mantis) to test that the Nix build steps work and run each of the Ops test suites.
 
-Unit Test Code Coverage Status [FIXME]
+You can check the latest build results of the current branch by clicking the status icon in the header of the Github file browser.
+
+Unit Test Code Coverage Status - TBD
+
+### Docs - FIXME: Update docs!
 
-// FIXME: Should we continue using this? or should we migrate to atlassian wiki?
 For more details on configuration and functionality check out our [wiki](http://mantis.readthedocs.io) (also at [wiki](https://github.com/input-output-hk/mantis/wiki))
 
 ### Download the client