rename fluent plugin and update docs

fluentd/fluent-plugin-grafana-loki/.gitignore

fluentd/fluent-plugin-grafana-loki/.rspec

fluentd/fluent-plugin-grafana-loki/.rubocop.yml

fluentd/fluent-plugin-grafana-loki/Dockerfile

fluentd/fluent-plugin-grafana-loki/Gemfile

fluentd/fluent-plugin-grafana-loki/README.md

fluentd/fluent-plugin-grafana-loki/Rakefile

fluentd/fluent-plugin-grafana-loki/bin/console

fluentd/fluent-plugin-grafana-loki/bin/setup

fluentd/fluent-plugin-grafana-loki/docker/Gemfile

...ntd/fluent-plugin-grafana-loki/docker/conf/fluentd-1.conf

...ntd/fluent-plugin-grafana-loki/docker/conf/fluentd-2.conf

fluentd/fluent-plugin-grafana-loki/docker/conf/fluentd.conf

fluentd/fluent-plugin-grafana-loki/docker/conf/loki.conf

fluentd/fluent-plugin-grafana-loki/docker/conf/systemd.conf

fluentd/fluent-plugin-grafana-loki/docker/docker-compose.yml

fluentd/fluent-plugin-grafana-loki/docker/entrypoint.sh

...nt-plugin-grafana-loki/fluent-plugin-grafana-loki.gemspec

.../fluent-plugin-grafana-loki/lib/fluent/plugin/out_loki.rb

...t-plugin-grafana-loki/spec/gems/fluent/plugin/data/syslog