Replace the ENV variable with a config file

So it's safer to configure, as we don't need to pass env variables
to a docker run service. Also it's easier to configure without
needing to pass a whole lot of env vars.

README.md

@@ -1,7 +1,42 @@
+## Usage
+
 ### Installation
 
-The easiest way is to run the docker container and set it to restart always. This basically makes it a system service that will always run.
+The easiest way this is to run the docker container and set it to restart always. This basically makes it a system service that will always run.
+
+To make it safe and avoid passing credentials we're using a configuration file.
 
 ```shell
-docker run --restart=always -e MODBUS_HOST=192.168.1.1 solaredge_modbus_mqtt:latest
+mkdir /etc/solaredge_modbus_mqtt
+chmod 700 /etc/solaredge_modbus_mqtt
+cp config.yaml-dist /etc/solaredge_modbus_mqtt/config.yaml
+docker run --name=solaredge_modbus_mqtt --restart=always --volume=/etc/solaredge_modbus_mqtt/config.yaml:/app/config.yaml  marijnkoesen/solaredge_modbus_mqtt:latest
+```
+
+
+## For developers
+
+### Building and running the docker image
+
+```shell
+docker build -t solaredge_modbus_mqtt:latest .
+cp config.yaml-dist config.yaml
+docker run --volume=$PWD/config.yaml:/app/config.yaml solaredge_modbus_mqtt:latest
+```
+
+
+### Running without docker
+
+```shell
+pip3 install -r requirements.txt
+cp config.yaml-dist config.yaml
+python3 solaredge_modbus_mqtt.py
+```
+
+
+### Running tests
+
+```shell
+pip3 install -r requirements.txt
+python3 -m unittest
 ```