Request: additional vars for desired, min, max capacity instead of having them all the same

[allantaylor8907]

Perhaps default cluster size to all the same but allow options for additional parameters for the desired, min, and max capacity. This allows use of some other tools to cycle AMI's that can only work by incrementing values in the cluster but this is blocked by having the max capacity the same as the desired capacity.

[brikis98]

A PR to add this is welcome!