Refactor of EKS and ASFF integration Job and instructions (#794)

* Refactor to use Configmap for EKS and ASFF integration

* newline

* markdown fix

* formatting fix

* Update docs/asff.md

Co-authored-by: Liz Rice <liz@lizrice.com>

* typo

* docs: remove section about rebuilding

* docs: reminder to specify kube-bench image for ASFF

Co-authored-by: Liz Rice <liz@lizrice.com>