WIP: Resolve "Profile/Timeline of build pipelines"

Closes #128

• Use of "changes" keyword is correct.
• Test jobs are skipped if no html, md or yaml has been changed in the associated commit.
• Test jobs are not skipped if html, md or yaml has been changed in the associated commit.
• The "changes" pattern given is correct and test jobs are not skipped in situations in which tests make sense. It is neither too restrictive nor too broad.