[BEAM-1385] Add license header to website Jenkins job descriptions

[kennknowles]

Be sure to do all of the following to help us incorporate your contribution
quickly and easily:

• Make sure the PR title is formatted like:
  [BEAM-<Jira issue #>] Description of pull request
• Make sure tests pass via mvn clean verify. (Even better, enable
  Travis-CI on your fork and ensure the whole test matrix passes).
• Replace <Jira issue #> in the title with the actual Jira issue
  number, if there is one.
• If this contribution is large, please file an Apache
  Individual Contributor License Agreement.

---

[coveralls]

Changes Unknown when pulling 838ef04 on kennknowles:groovy-RAT into ** on apache:master**.

[asfbot]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/beam_PreCommit_Java_MavenInstall/7052/
--none--

[kennknowles]

Because this unbreaks the build, I am going to merge before review.

[kennknowles]

R: @davorbonaci

[kennknowles]

(or any committer, since we are now switching which side of the Earth is in daylight :-)

[davorbonaci]

LGTM.

Thanks @kennknowles; much appreciated. FYI @jasonkuster.

[jasonkuster]

@peihe created #1911 to fix too, looks like this got in before his.