[readme] Add build badge for future automated testing

README.md

@@ -39,6 +39,8 @@ See the file `LICENSE.md` for full copying permissions.
 Automated Testing
 -----------------
 
+[![build status](https://git.iws.uni-stuttgart.de/dumux-repositories/dumux-lecture/badges/master/build.svg)](https://git.iws.uni-stuttgart.de/dumux-repositories/dumux-lecture/commits/master)
+
 The simulations in DuMuX-Lecture are tested automated using buildbot.
 The test suite consists of the actual simulations adjusted to smaller run times.
 Click <a href="https://git.iws.uni-stuttgart.de/buildbot/#/builders" target="_blank">here</a>