docs(readme): add README.md

README.md

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+# Graftorio Multiplayer
+
+Inspired by the original Graftorio and Gratorio2 fork, this mod and docker container provide exporting of production statistics to Grafana via Prometheus.
+
+At this time, this project is a **WORK IN PROGRESS**, so please bear with any issues you find and report them or submit a PR.
+
+This mod is designed and intended for running on a Factorio server.
+
+# Installation
+
+This whole setup utilizes Docker Compose, and a template configuration for it is provided. If you already have a Factorio, Grafana, or Prometheus server, then feel free to remove those parts of the configuration and point everything at your own. If you go that route, I assume you know what you're doing.
+
+First, install Docker Compose. Once you have it, do the following:
+
+```shell
+git clone https://github.com/larkwiot/graftorio-mp
+cd graftorio-mp
+
+# the network=host is for pip
+docker build --network=host -t graftorio-mp:latest .
+
+mkdir -p /opt/docker
+cp docker-compose.yml /opt/docker
+cd /opt/docker
+docker compose up -d
+```
+
+Install the mod on your server either by grabbing a release, using your Factorio client, or by cloning and then zipping up this repository (remember to rename the zip appropriately with the version number).
+
+You will also need to configure Prometheus to scrape the exporter. You can do that with a config that looks like this:
+
+```yaml
+# /opt/docker/prometheus/conf/prometheus.yml
+global:
+  scrape_interval: 15s
+  scrape_timout: 10s
+  evaluation_interval: 1m
+
+  query_log_file: /opt/bitname/prometheus/data/prom.log
+
+scrape_configs:
+  - job_name: factorio
+    static_configs:
+      - targets:
+          # or whatever port you specified in the docker-compose.yml
+          - graftorio-mp:9102
+```
+
+Remember to restart Prometheus after changing the config:
+```shell
+docker compose restart prometheus
+```
+
+# How it Works
+
+This setup is made up of two components:
+1. A Factorio mod that periodically dumps statistics to a JSON file
+2. A Dockerized Python Prometheus Client that reads the JSON when scraped by Prometheus and ships the data back
+
+By default, the data is dumped for every item every 15 seconds to match Prometheus' default scrape interval. You could change that in `control.lua`.