tutorial/Eureka: fix healthcheck instructions

Eureka does have a healthcheck endpoint (/healthcheck). The "HTTP:7001/api/v2/view/instances;_limit=1" thing seems to be a copy-paste issue, because it's the URL used for the Edda project.

Since it's the same endpoint as Asgard, I believe it's safe to just instruct users to follow asgard instructions, replacing only the name.