* chore: updating some user retirement documents
* removing some Jenkins documentation which is specific to 2u's implementation, and links to the old org's wiki
* updating some markup that was preventing images from rendering. Tested locally with a docs bill to make them render now.
FIXES: APER-3981
* chore: adding a filewith a revised image
* another file with a revised image which didn't make it into the original commit
I'm not sure how this worked before but I corrected to use the
`graphviz` directive and then full graphviz graph syntax which seemed to
fix whatever issues it was having.
