Docs updates following PR #2442 (#2448)

* Restore Gemfile and Gemfile.lock

* Update mac install steps. update min python versions. & update some css

* Update _layout.scss

* update position of os-icons

* update some logos

* Warn out-of-date OpenBSD steps

* Update docs to target python 3.9 as minimum version.

* Reorganize options/config sections

* Update commands and options for new/extra search services.

* Add change log for config-cli-tool changes

* Update troubleshooting.md

* minor updates to FAQ

* Add YtdlpSourceAddress