Add cheat for docker

cheat/cheatsheets/docker

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+# Start docker daemon
+docker -d
+
+# start a container with an interactive shell
+docker run -ti <image_name> /bin/bash
+
+# inspect a running container
+docker inspect <container_name> (or <container_id>)
+
+# Get the process ID for a container
+# Source: https://github.com/jpetazzo/nsenter
+docker inspect --format {{.State.Pid}} <container_name_or_ID>
+
+# List the current mounted volumes for a container (and pretty print)
+# Source:
+# http://nathanleclaire.com/blog/2014/07/12/10-docker-tips-and-tricks-that-will-make-you-sing-a-whale-song-of-joy/
+docker inspect --format='{{json .Volumes}}' <container_id> | python -mjson.tool
+
+# list currently running containers
+docker ps
+
+# list all containers
+docker ps -a
+
+# list all images
+docker images