create documentation on rsyslog use in containers

[rgerhards]

[deoren]

Since this is an long-running ticket on the same topic, I'll post the suggestions I made as doc comments here.

These remarks are in regards to the source/containers/container_features.rst file.

Upon start, rsyslog checks if it is running as pid 1. If so, this is a clear indication it is running inside a container.

• Explain why this is a clear indication. Perhaps make a quick reference to what normally holds pid 1 for anyone new to UNIX process management

This changes some parameter defaults

• Add details explaining WHY the parameter defaults were changed.

refs #494

[deoren]

TODO: Reference official Docker Hub (page, profile, id?):

https://hub.docker.com/u/rsyslog/

[rgerhards]

I'll add it when I finally modify the PR ;-)

[deoren]

@rgerhards: I'll add it when I finally modify the PR ;-)

Yep. Is it helpful to add standalone/misc items like that to existing tickets (which appear to be works in progress) or as separate tickets? I was thinking the former based on the state.