update codeblock syntax

_episodes/01-prep.md

@@ -50,32 +50,32 @@ ssh registryN-private
 
 First we'll see what docker nodes are available:
 
-``` bash
+``` shell
 docker node ls
 ```
 
 which should result in something that looks like this:
 
-``` bash
+``` shell
 ID                            HOSTNAME                                       STATUS              AVAILABILITY        MANAGER STATUS      ENGINE VERSION
 8tuwrbfdci97tfn9nqoinic0o *   registry1-private.comanage.incommon.training   Ready               Active              Leader              19.03.4
 ```
 
 You can also see the list of containers that are available by running the docker ps command. (NOTE, there shouldn't be any Docker containers because we haven't set them up yet. This command will confirm that this is true.)
 
-``` bash
+``` shell
 docker ps
 ```
 
 which should result in just showing the headers for the list of containers. It will look something that looks like this
 
-``` bash
+``` shell
 CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
 ```
 
 _NOTE: You can also use `sudo` without a password, but you probably will not need it in this session. For example,_
 
-``` shellscript
+``` shell
 [training@registry1-private ~]$ sudo /usr/bin/whoami
 root
 ```