Add example logs for `runner` and `json` log-format options - docs

What does this MR do?

Add example logs for runner and json log-format options. This is in response to this comment posted on the Runner advanced-configuration documentation page.

Moving docs to a new location?

• Make sure the old link is not removed and has its contents replaced with a link to the new location.
• Make sure internal links pointing to the document in question are not broken.
• Search and replace any links referring to old docs in GitLab Runner's source code