[readme] Fix coverage link

README.md

@@ -58,7 +58,7 @@ Click <a href="https://git.iws.uni-stuttgart.de/buildbot/#/builders" target="_bl
 to see the latest builds (clicking on a build
 number will show a detailed overview of the build).
 
-[![coverage report](https://git.iws.uni-stuttgart.de/dumux-repositories/dumux-coverage/badges/master/coverage.svg)](https://git.iws.uni-stuttgart.de/dumux-repositories/dumux-coverage/commits/master)
+[![coverage report](https://git.iws.uni-stuttgart.de/dumux-repositories/dumux-coverage/badges/master/coverage.svg)](https://pages.iws.uni-stuttgart.de/dumux-repositories/dumux-coverage/)
 
 A weekly coverage report of the test suite is created by gcovr/gcov. The report
 currently doesn't include non-instantiated code, so the real coverage is likely lower. However,