docker-machine: Deprecate both plugin and completion file

plugins/available/docker-machine.plugin.bash

@@ -1,13 +1,5 @@
+# shellcheck shell=bash
 cite about-plugin
 about-plugin 'Helpers to get Docker setup correctly for docker-machine'
-
-[ -z ${BASH_IT_DOCKER_MACHINE+x} ] && BASH_IT_DOCKER_MACHINE='dev'
-
-# Note, this might need to be different if you use a machine other than 'dev'
-if [[ `uname -s` == "Darwin" ]]; then
-  # check if dev machine is running
-  docker-machine ls | grep --quiet "$BASH_IT_DOCKER_MACHINE.*Running"
-  if [[ "$?" = "0" ]]; then
-    eval "$(docker-machine env $BASH_IT_DOCKER_MACHINE)"
-  fi
-fi
+_log_error '"docker-machine" is now deprecated, and as such the plugin for it is also deprecated.
+Please disable this plugin.'