config docs: add examples to mode()

Improved by comments from Petr.
3 jobs for mode-examples in 8 minutes and 39 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #6337
docker linux amd64
build:linux:amd64

00:05:56

 
  Test
passed #6339
docker linux amd64
deckard:linux:amd64

00:02:43

passed #6338
docker linux amd64
test:linux:amd64

00:02:17