Resource on the line of link and border

An architecture diagram may be drawn that places resources along links and boundaries. Examples: Internet gateways, VPN connections, etc.

## On the line of link

## On the line of border
Use the 16-wind rose to specify the location of the resource. See details of [doc/links.md](https://github.com/awslabs/diagram-as-code/blob/main/doc/links.md)

Start with doc/links.md to understand how the 16-wind rose specifies resource locations, then inspect the existing link and boundary placement entry points. Done means architecture diagrams can place resources on link lines and borders, including the Internet gateway and VPN connection cases described in the issue.

Written by the indexing model from the issue text.