Add documentation for non-central settings.xml updates

[scotty6435]

Our enterprise environment means we use internal repos rather than the default central repo for Maven artefacts. Because of this, we had to amend the settings.xml file with a new repository with the ID "archetype" as per https://maven.apache.org/archetype/maven-archetype-plugin/archetype-repository.html in order to resolve the artefact and create a new project.

This isn't documented anywhere in this project but given Adobe's audience, this should be a reasonably common occurrence. Adding a small "if" case with a link to the page should be enough to remind users who do not have a 'central' ID repository in-use will have to take action.