Clarify Modrinth URL structure in documentation (#3197)

Author: mishl-dev

docs/mods-and-plugins/modrinth.md

@@ -2,7 +2,7 @@
 
 [Modrinth](https://modrinth.com/) is an open source modding platform with a clean, easy to use website for finding [Fabric, Forge, etc mods](https://modrinth.com/mods) and [Paper, etc plugins](https://modrinth.com/plugins), and [datapacks](https://modrinth.com/datapacks). At startup, the container will automatically locate and download the newest versions of mod/plugin files that correspond to the `TYPE` and `VERSION` in use. Older file versions downloaded previously will automatically be cleaned up.
 
-- **MODRINTH_PROJECTS** : comma or newline separated list of project slugs (short name) or IDs. The project ID is located in the "Technical information" section. The slug is the part of the page URL that follows `/mod/`:
+- **MODRINTH_PROJECTS** : comma or newline separated list of project slugs (short name) or IDs. The project ID is located in the "Technical information" section. The project slug is the part of the URL that follows `/mod/`, `/plugin/`, or `/datapack/`. For example:
   ```
     https://modrinth.com/mod/fabric-api
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