Same default CIDR for Mgmt VPC
In the Reference Architecture form, the same default CIDR block is used for all account Mgmt VPC. Why is that?
The `mgmt` VPC in the Reference Architecture is only used for the ECS Deploy Runner component of [Gruntwork Pipelines](https://gruntwork.io/pipelines/). The ECS Deploy Runner is a self-sufficient component that runs entirely on serverless architecture. As such, you shouldn't need to access the components directly over the network, since all the inbound interaction is handled via AWS APIs (specifically, invoke lambda action). To avoid cluttering any IP spaces that your organization uses, it is recommended not to setup peering to this VPC, as it is not necessary. Given that, the CIDR block used for these VPCs do not matter, and thus the same default is used for all of them. **CAVEAT**: When Jenkins is selected in the Reference Architecture form, Jenkins will be deployed in to the `shared` account `mgmt` VPC. In this case, you may want to select a different CIDR block just for that account.