Add example using context with CLI.

Home.md

@@ -30,6 +30,12 @@ Also available from CLI:
 echo '{{"hello" | capitalize}}' | npx liquidjs
 ```
 
+If you pass a path to a JSON file or a JSON string as the first argument, it will be used as the context for your template.
+
+```bash
+echo 'Hello, {{ name }}.' | npx liquidjs '{"name": "Snake"}'
+```
+
 ## More Demos
 
 There's [a live demo][jsfiddle] on JSFiddle, and a list of demo projects in [the demo/ directory][demo-dir]