fix: add use as npm module directions

Author: seveibar

README.md

@@ -17,6 +17,16 @@ npm install -g udt-collaboration-server
 udt-collaboration-server --port 80
 ```
 
+## Usage as an npm module
+
+```javascript
+const runCollaborationServer = require("udt-collaboration-server")
+const server = runCollaborationServer({ port: 3000 })
+
+// Later...
+server.close()
+```
+
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