Docker in docker is not supported

[martinda]

When the configuration specification contains build: "true" like so:

buildSettings:
  docker:
    build: "true"

The war file generation fails with:

java.io.IOException: Cannot run program "docker" (in directory "tmp/output"): error=2, No such file or directory

This was discovered as part of PR #141

[martinda]

Solution for now is to set the build to false:

buildSettings:
  docker:
    build: "false"
    tag: "tag1"
    base: "jenkins/jenkins:2.235.5-lts-jdk11"

[sladyn98]

Set the build option to false so that the user is setup for success in the war generation.