add missing step to the README
add missing step to the README

Also corrects some typos and removes unnecessary whitespace.
GoogleCloudPlatform/appengine-java-vm-runtime,GoogleCloudPlatform/appengine-java-vm-runtime,aozarov/appengine-java-vm-runtime,GoogleCloudPlatform/appengine-java-vm-runtime,jetty-project/appengine-java-vm-runtime,GoogleCloudPlatform/openjdk-runtime,aglne/appengine-java-vm-runtime,jboynes/appengine-java-vm-runtime,ludoch/appengine-java-vm-runtime,GoogleCloudPlatform/jetty-runtime,jboynes/appengine-java-vm-runtime,jetty-project/appengine-java-vm-runtime,ludoch/appengine-java-vm-runtime,GoogleCloudPlatform/openjdk-runtime,GoogleCloudPlatform/jetty-runtime,jetty-project/appengine-java-vm-runtime,aozarov/appengine-java-vm-runtime,aglne/appengine-java-vm-runtime,ludoch/appengine-java-vm-runtime,jboynes/appengine-java-vm-runtime,GoogleCloudPlatform/openjdk-runtime,aozarov/appengine-java-vm-runtime,GoogleCloudPlatform/jetty-runtime,GoogleCloudPlatform/jetty-runtime