DOC: review FunctorImageFilter doc

4 jobs for 1868-functorfilter-in-cookbook in 3 minutes and 45 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Precheck
canceled #2970
fast-build

00:03:45

 
  External
passed cdash:debian-unstable-gcc

passed cdash:otb-centos-superbuild-base

passed cdash:ubuntu-18.04-llvm