Update docs executor titles

To be grammatically correct, `E` should be lower case.

closes #4441
5 jobs for docs/4441-follow-up-from-wip-add-custom-executor-documentation in 5 minutes and 9 seconds
Status Job ID Name Coverage
  Prebuild
passed #248680463
check feature flags docs

00:01:54

manual #248680457
allowed to fail manual
review-docs-deploy
 
  Test
passed #248680469
docs lint

00:01:45

passed #248680466
allowed to fail
license_management

00:03:12

 
  Cleanup
manual #248680471
allowed to fail manual
review-docs-cleanup