Update Fabric docs to use correct mod ID (#52)

Previously the documentation for the [Fabric](https://fabricmc.net/)
Cloud API implementation stated that developers should depend on cloud
with a mod-id of `cloud` in their `fabric.mod.json`
(https://cloud.incendo.org/minecraft/modded/fabric/#fabricmodjson),
however we were informed that the correct mod ID is `cloud-fabric`.

This is a simple PR that fixes that.

docs/minecraft/modded/fabric.md

@@ -43,7 +43,7 @@ Merge the following into your `fabric.mod.json`:
 ```json
 {
   "depends": {
-    "cloud": "*"
+    "cloud-fabric": "*"
   }
 }
 ```