Example health check outputs are out of date

Problem to solve

The Health Check documentation includes two example outputs: readiness and liveness. Both output examples are out of date, and need to be updated. For example, both checks report on the status of gitaly, but neither example includes mention of gitaly's status.

Source: https://docs.gitlab.com/ee/user/admin_area/monitoring/health_check.html

Proposal

Update the examples in the Health Check documentation.