Update README.md

Author: alexmacarthur

README.md

@@ -7,14 +7,17 @@ A collection of Docker Compose files I've used to quickly spin local databases o
 Because I've oft needed them, particularly when I just don't wanna deal with the hassle of spinning up a DB on my own system.
 
 ## How? 
-Clone the repo or copy a `docker-compose.yml` file to your system, `cd` into that directory, and turn it on with `docker-compose up`. For a full reference on how to use Docker Compose, [go here](https://docs.docker.com/compose/reference/).
+Clone the repo or copy a `docker-compose.yml` file to your system, `cd` into that directory, and turn it on with `docker-compose up`. You may also use a `docker-compose.override.yml` file inside this repository to customize a container. For a full reference on how to use Docker Compose, [go here](https://docs.docker.com/compose/reference/).
 
 ## Local Persistence
-In each setup a docker managed volume is created to persist the database. This can be deleted by Docker compose by passing the "-v" option when deleting the container(s).
+In each setup, a managed volume is created to persist each container's data. This volume can be deleted by passing the `-v` option when deleting the container.
 
 ```
 docker-compose down -v
 ```
 
 ## Authentication
-For authenticating as super user with each of these examples, `root` should be the username and `password` should be the password.
+For authenticating as super user with each of these examples, `root` is the username and `password` is the password.
+
+## Contributions
+If you have a Docker Compose configuration for a database not seen here, please consider making a pull request to add it!