docs: clearer docs for plugin download host configuration (#1716)

docs/source/getting-started.md

@@ -49,9 +49,9 @@ Rover is distributed on npm for integration with your JavaScript projects.
 Internally, the `npm` installer downloads router binaries from `https://rover.apollo.dev`. If this URL is unavailable, for example, in a private network, you can point the `npm` installer at another URL in one of two ways:
 
 - by setting the `APOLLO_ROVER_DOWNLOAD_HOST` environment variable
- - *note*: This value must be set if you also want the rover plugins to be downloaded from this host
-- by adding the following to your global or local `.npmrc`:
-  
+
+> **Note**: This environment variable also changes the host that plugins for `rover supergraph compose` and `rover dev` are downloaded from.
+
 ```ini
 apollo_rover_download_host=https://your.mirror.com/repository
 ```