Update launch.md

Documentation/launch.md

@@ -1,8 +1,10 @@
 # Running castled
   1. Copy your `castled` binary to one or more CoreOS machines
   2. Generate a discovery token
-   `token_size=3`
-   `discovery_token=$(curl -w "\n" 'https://discovery.etcd.io/new?size=$token_size' 2>nil)`
-   `echo $discovery_token`
+```
+token_size=3
+discovery_token=$(curl -w "\n" 'https://discovery.etcd.io/new?size=$token_size' 2>nil)
+echo $discovery_token
+```
   3. Start the castled process on each machine. Don't forget to set or replace your $discovery_token variable 
    `./castled --discovery-url=$discovery_token --private-ipv4=${COREOS_PRIVATE_IPV4} --devices=sdb,sdc,sdd --force-format=true`