Update default value for "Facet parameter limit"

Problem/Motivation

In this LinkedIn comment, @bburg (the module maintainer) said about the "Facet parameter limit" field:

I'd say 5 is a good medium. If you are really struggling with these bots, feel free to set it lower, but understand that risks pulling blocking human users. I think the module actually defaults to 1, which I need to fix.

I think it would also be a good idea to offer similar explanation in the help text for that field.

Steps to reproduce

n/a

Proposed resolution

Update default value and add help text per above.

Remaining tasks

Update default value and add help text per above.

User interface changes

Update default value and add help text per above.

API changes

Data model changes