Description of change
Bootstrap command help has been pointing to stale docs site. Rather than changing the links to point to the newer site that is going to be obsolete soon as well, this PR goes to the source of truth - the code - to list available config keys.
Drive-by: fixes to some variables that conflict with import names.
QA steps
run 'juju help bootstrap' to see newer help.
Bug reference
https://bugs.launchpad.net/juju/+bug/1840470
该提问来源于开源项目：juju/juju
