Add jq to Prerequisites or remove usage?

[natict]

Since jq is being used, e.g. in https://github.com/prabhatsharma/kubernetes-the-hard-way-aws/blob/master/docs/03-compute-resources.md#instance-image

It might be a good idea to add it to the Prerequisites page or avoid using it (if possible). Hopefully I'll find the time later this week to turn this issue into a PR :)