improve description of --s3-bucket-location option
improve description of --s3-bucket-location option

"location" is rather unclear (directory location?!), "region" is more
clearer what the option intends to configure

copied from docs/configuration/advanced-configuration.md

hu19891110/gitlab-ci-multi-runner,soiff/gitlab-ci-multi-runner,hu19891110/gitlab-ci-multi-runner,soiff/gitlab-ci-multi-runner,soiff/gitlab-ci-multi-runner,hu19891110/gitlab-ci-multi-runner