[EKS] Jenkins optional module.

[ruecarlo]

the optional section with Jenkins uses helm pointing to the latest version. This means the instructions in the documentation may not work if there has been a change in the latest version deployed by Helm or if the plugins that come with it have changed as a result.

As part of the workshop we should stick to best practices and install a specific version that ensures changes in Helm Jenkins repository do not affect current runs. As a consequence the version of Jenkins used will have to be updated manually in each new version.