Update the-application.rst

Two modification need to be made
1)module/Checklist/src/Checklist/TaskMapper.php to module/Checklist/src/Checklist/Model/TaskMapper.php

2)In  getServiceConfig() TaskMapper to Checklist\Model\TaskMapper
Merge remote-tracking branch 'origin/pr/1242' into hotfix/1242
[#1242] service name

- Narrative refers to service name consistently as `TaskMapper`; however, the
  one place it's retrieved, in the controller, it refers to the FQCN; changed so
  the latter refers to the narrative service name.
Merge branch 'hotfix/1242'

Close #1242