Adding existing ElastiCache cluster to serverless.yaml

I created an ElastiCache cluster and want to added it to my serverless.yaml so my lambdas can access it. I have seen examples that seem to want CloudFormation to build it but not just to add it.
I would think it would be added to the resources section but it is not clear.

In the past, I have added an action to my iamrolestatements. I figure that I need to add AddTagsToResourse action but, again, it is not clear where I find the short form action reference ( ex. ses:SendEmail allows the resource to use SES to send email.). What is the short for ElastiCache? EC? Where would I find that information?