predict docs: fix the description of expiring records

The description didn't match the reality.  Change docs for now,
even though 1% seems a bit too little to me personally.
5 jobs from predict in 24 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Build
canceled #73053
docker linux amd64
build:linux:amd64

passed #28538
docker linux amd64
build:linux:amd64

00:00:25

 
  Test
passed #28540
docker linux amd64
deckard:linux:amd64

00:00:23

canceled #28541
docker linux amd64 allowed to fail
respdiff:linux:amd64

00:00:05

passed #28539
docker linux amd64
test:linux:amd64

00:00:18