Update readme files

javascript/README.md

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+# FairHopper JavaScript SDK
+
+Requirements:
+- Node 1.16+
+
+## Running demo
+
+Check `demo.js` for usage example.
+
+Edit `demo.js` and configure FairHopper Game host settings:
+
+```javascript
+const FAIRHOPPER_HOST = "http://127.0.0.1";
+const FAIRHOPPER_PORT = 8010;
+```
+
+Run example using node:
+
+```sh
+node demo.js
+```