Cache documentation files for faster CI

6 jobs for docu-speedup in 47 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Prepare
passed docker #1230513
shell linux

00:00:09

 
  Test
passed test:export-against-exported-files #1230516
docker

00:00:13

passed test:export-against-imported-files #1230515
docker

00:00:13

passed test:import #1230514
docker

00:00:13

 
  Generate
passed documentation #1230568
docker

00:00:23

passed documentation #1230517
docker

00:02:33