Simplify docker networking and clarify the README, fixes #8

.gitignore

@@ -1 +1,2 @@
 /target
+config.toml

README.md

@@ -15,17 +15,21 @@ Ensure you have a [rust toolchain](https://www.rust-lang.org/tools/install) inst
 In order to set up a test instance of mariadb in a docker container, run the following command:
 
 ```bash
-docker run --rm --name mariadb -e MYSQL_ROOT_PASSWORD=secret -d mariadb:latest
+docker run --rm --name mariadb -e MYSQL_ROOT_PASSWORD=secret -p 3306:3306 -d mariadb:latest
 ```
 
-You should then create a config file, and adjust the hostname to the IP address of the docker container.
+This will start a mariadb instance with the root password `secret`, and expose the port 3306 on the host machine.
+
+
+Run the following command to create a configuration file with the default settings:
 
 ```bash
 cp ./example-config.toml ./config.toml
-DOCKER_IP_ADDRESS="$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' mariadb)"
-sed -i "s/host = \"localhost\"/host = \"${DOCKER_IP_ADDRESS}\"/" ./config.toml
 ```
 
+If you used the docker command above, you can use these settings as is, but if you are running mariadb/mysql on another host, port or with another password, adjust the corresponding fields in `config.toml`.
+This file will contain your database password, but is ignored by git, so it will not be committed to the repository.
+
 You should now be able to connect to the mariadb instance, after building the program and using arguments to specify the config file.
 
 ```bash