add new line

base/centos-full:7

@@ -22,4 +22,4 @@ FROM centos:7.4.1708
  RUN ssh-keygen -t rsa -P "" -f ~/.ssh/id_rsa -q
  RUN cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
  RUN chmod og-wx ~/.ssh/authorized_keys 
- RUN ssh-keyscan -H -t rsa localhost,`hostname -i`  >> ~/.ssh/known_hosts
\ No newline at end of file
+ RUN ssh-keyscan -H -t rsa localhost,`hostname -i`  >> ~/.ssh/known_hosts