Update for the example command line options.

Change-Id: Ida6e882d1014cdc5e55383a5d5ba8fa0e824a693

It is now possible to deploy either 1.x or 2.x version of Prometheus.
The new 2.x version introduces breaking changes in terms of storage
format and command line options.

Change-Id: I80cc6f1947f3740ef04b29839bfa655b14fae146
Co-Authored-By: Radosław Piliszek <radoslaw.piliszek@gmail.com>

This provides a generic mechanism to include extra files
that you can reference in prometheus.yml, for example:

scrape_targets:
  - job_name: ipmi
    params:
      module: default
    scrape_interval: 1m
    scrape_timeout: 30s
    metrics_path: /ipmi
    scheme: http
    file_sd_configs:
    - files:
      - /etc/prometheus/extras/file_sd/ipmi-exporter-targets.yml
      refresh_interval: 5m

Change-Id: Ie2f085204b71725b901a179ee51541f1f383c6fa
Related: blueprint custom-prometheus-targets

This provides a mechanism to scrape targets defined outside of kolla-ansible.

Depends-On: https://review.opendev.org/#/c/685671/
Change-Id: I0950341b147bb374b4128f09f807ef5a756f5dfa
Related: blueprint custom-prometheus-targets

Change-Id: I8bb39eaf8a4239c37fcbf91b55ec8003542e2506