Added docker link

README.md

@@ -19,7 +19,13 @@ docker/ - docker image to do WCRT analysis
 The directory contains a docker file and a prebuilt PATMOS toolchain
 that can be used for WCRT analysis, including our minor adaptions on
 the official toolchain. The docker image includes a clone of dOSEK and
-the platin repository. In order to reproduce the TMR benchmark, just
+the platin repository. You can either build the docker image yourself
+or pull it from Dockerhub
+
+    docker pull stettberger/syswcet # or
+    make docker-build
+
+In order to reproduce the TMR benchmark, just
 log into the docker image via SSH (user/password: dosek/dosek):
 
     make docker-start