fix(docs): Change path.settings to path.config

[joostdecock]

There is no such thing as path.settings so I presume this is supposed to be path.config.
(if there is such a thing as path.settings it is not listed in the logstash.yml reference documentation.)

Release notes

[rn:skip]

What does this PR do?

Fixes an error in the documentation.

Why is it important/What is the impact to the user?

Documentation will improve.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files (and/or docker env variables)
• I have added tests that prove my fix is effective or that my feature works

How to test this PR locally

You can just read the diff

[joostdecock]

Please label this PR with the release version and one of the following labels, depending on the scope of your change

I have no triage rights on this repo, so I presume it's not intended for me.
That being said, the label should be doc and the version is current, the error can be seen here: https://www.elastic.co/guide/en/logstash/current/multiple-pipelines.html