diff --git a/docs/add-ons/configuration.md b/docs/add-ons/configuration.md
index b99dd55c..209da0c6 100644
--- a/docs/add-ons/configuration.md
+++ b/docs/add-ons/configuration.md
@@ -108,7 +108,7 @@ The config for an add-on is stored in `config.json`.
 | --- | ---- | -------- | ----------- |
 | name | string | yes | Name of the add-on
 | version | string | yes | Version of the add-on
-| slug | string | yes | Slug of the add-on
+| slug | string | yes | Slug of the add-on. This needs to be unique in scope to the [repository](repository.md) that the add-on is published in, and URI friendly.
 | description | string | yes | Description of the add-on
 | arch | list | yes | List of supported arch: `armhf`, `armv7`, `aarch64`, `amd64`, `i386`.
 | machine | list | no | Default it support any machine type. You can select that this add-on run only on specific machines.
@@ -161,7 +161,6 @@ The config for an add-on is stored in `config.json`.
 | stage | string | no | Default `stable`. Flag add-on with follow attribute: `stable`, `experimental`, `deprecated`
 | init | bool | no | Default `True`. Make it possible to disable the docker default system init because the image have his own init system.
 
-
 ### Options / Schema
 
 The `options` dictionary contains all available options and their default value. Set the default value to `null` if the value is required to be given by the user before the add-on can start, and it show it inside default values. Only nested arrays and dictionaries are supported with a deep of two size. If you want make an option optional, put `?` to the end of data type, otherwise it will be a required value.