Administrative: Document how to use Eclipse CI and backup Jenkins configuration from the Eclipse CI

[jhanders34]

From the specifications call today, we discussed some retrospective items about Jenkins CI. Two areas were discussed:

• Presently the component and platform specifications do not consistently have their CI jobs documented in a wiki in their repository to make it easy for any committer to be able to run the jobs to create a release of the API, spec, javadoc and TCK and how to publish those out to staging and maven. The request is to get it documented.
• As part of the fallout from the Eclipse storage system outage, it was determined that none of the CI configuration data is backed up outside of the CI itself and we would have lost all configuration and would have to do a lot of work to get it back for every component. The ask is to back up the configuration for CI jobs either using a JenkinsFile to be used to build or to at least back it up to a Jenkins file to be able to get it if the CI configuration is lost again.