Remove old options from SQLFluff config file

[tunetheweb]

Fixes #2493

The SQLFluff config options changed quite a bit in v2. Rather than continually trying to keep these in line, let's put the bare minimum in, since they are the defaults and commented out.

Proposed Changes

1. Time down the config file to the bare minimum and link to the docs

Readiness Checklist

Author/Contributor

• Add entry to the CHANGELOG listing the change and linking to the corresponding issue (if appropriate) - N/A
• If documentation is needed for this change, has that been included in this pull request - N/A

Reviewing Maintainer

• Label as breaking if this is a large fundamental change
• Label as either automation, bug, documentation, enhancement, infrastructure, or performance

[nvuillam]

Thanks for the PR :)