Update Docker image of Ansible (2.7.0 -> 2.8.1)

docs/ansible.md

@@ -50,7 +50,7 @@ docker run -it --rm \
 -v `pwd`:/work \
 -v $HOME/.ssh/id_rsa:/root/.ssh/id_rsa:ro \
 --entrypoint=/bin/sh \
-devture/ansible:2.7.0-r1
+devture/ansible:2.8.1-r0
 ```
 
 The above command tries to mount an SSH key (`$HOME/.ssh/id_rsa`) into the container (at `/root/.ssh/id_rsa`).