NMS-13870: Add Nephron documentation

[indigo423]

Depends on OpenNMS/nephron#43 and adds Nephron to be published on docs.opennms.com

JIRA: https://issues.opennms.org/browse/NMS-13870

[Bonrob2]

LGTM.

[Bonrob2]

Looking at this again, and wondering if we need separate docs for nephron. Is it going to be like Helm, or more like Sentinel/Minion? If the latter, we should just add nephron-related content to the main docs. Thoughts?

[indigo423]

Looking at this again, and wondering if we need separate docs for nephron. Is it going to be like Helm, or more like Sentinel/Minion? If the latter, we should just add nephron-related content to the main docs. Thoughts?

Core, Sentinel, and Minion are in the same GitHub repository and have the exact same release life cycle. They share the same version number. Nephron is a bit more like ALEC or Helm, it has its own software life cycle and release process. You want to update and publish Nephron docs independently with Nephron releases and you don't want to entangle your Nephron docs changes with Horizon/Meridian releases.

[indigo423]

If we merge the PR as it is now, we get the first docs published with the next 0.3.2 release from Nephron. The current release 0.3.1 doesn't have docs.

[Bonrob2]

If we merge the PR as it is now, we get the first docs published with the next 0.3.2 release from Nephron. The current release 0.3.1 doesn't have docs.

I have docs ready to go as a first draft. (OpenNMS/nephron#47)

[indigo423]

FYI: The site.zip artifact from the build doesn't show the Nephron docs, the filter is set to Nephron version 0.3.2+ which isn't released with the Antora docs yet. They will show up when we have a Nephron 0.3.2 released.