add explanation

Setup/README.md

@@ -31,7 +31,7 @@ to perform these steps for you. The user that wants to run `docker` needs to
 be in the docker group. If you have added yourself to the docker group, don't
 forget to log out and back in again.
 
-## Manual how to set up latest fenix image in Docker
+## Set up latest Fenix image in Docker
 Pull the latest `Fenics` Docker image
 
     docker pull quay.io/fenicsproject/stable:latest