Update contributing.md

docs/contributing.md

@@ -3,3 +3,6 @@ If you would like to contribute code you can get started by installing npm and y
 
 ## Contributing generator data
 If you don't know how to code but would still like to help, you can edit the [generator data file](https://github.com/Durtur/Dungeoneer/blob/master/data/generators/names.json). As with code, create a pull request with your changes. 
+
+## Adding sound effects
+To add more sounds to the default sound library, you can add a sound to the [sound folder](https://github.com/Durtur/Dungeoneer/tree/master/app/mappingTool/sounds), and if attribution is required add that to [sound attr.js](https://github.com/Durtur/Dungeoneer/blob/master/app/sound%20attr.js). Then create a pull request, including information regarding where the sound is from.