README: node: Added hint about apt repo source

README.md

@@ -42,7 +42,7 @@ Following roles have been defined for making a server configuration easy:
   - **static** sets up a static web root
   - **upstream** sets up an upstream accessible to nginx virtual servers
 - **node** defines roles for setting up node applications
-  - **application** installs the main application
+  - **application** installs node (installs from node official repository)
 - **server** defines roles using different kind of server applications, applications will be configured using separated system users
   - **firefox-sync** sets up a Firefox sync server for bookmarks, history, etc.
   - **gitea** sets up a git repository using *Gitea* as web overlay