Improve documentation and help commands around slum

- Add the job duration to the docs example
- Add more information to the help command
9 jobs for 186-slurm-documentation-unclear in 3 minutes and 46 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #990201
documentation

00:01:43

passed #990196
example-ini-file-builds

00:00:37

passed #990199
example-ini-file-pesummary

00:03:16

passed #990197
injection-regression-test

00:03:45

passed #990194
precommits-py3.6

00:00:55

passed #990193
precommits-py3.7

00:00:54

passed #990200
python-3.6

00:00:53

passed #990195
python-3.7

00:00:59

71.0%
passed #990198
review-test-build

00:00:23