should-vdj.md: Fix URL

Why was this wrong URL not detected earlier?!
3 jobs for doc/credits in 1 minute and 46 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test Tools
passed #661407
test_tools

00:00:09

 
  Tgz Release
passed #661408
cidocker
build_doc

00:01:28

 
  Deploy Prod
passed #661409
manual
deploy_doc

00:00:08