Docs: Removed rogue "(TODO)" note in FLAG_SHOW_LIGHTS member

Status: Ready for review
Note: This is a Javadoc only change.

Changes: Removed unnecessary "(TODO)" note.

Test: Build the docs with "make ds-docs" and staged updated content.

Staged content:
go/dac-stage/reference/android/app/Notification.html#FLAG_SHOW_LIGHTS

Bug: 20150478
Change-Id: I3a7fc0414ccb6f52e9b4919031a93ca1a7a29336