add readme

README.org

+* Installation
+
+#+begin_src sh
+  npm install
+  npm run build
+#+end_src
+
+* Sensors
+** Documentation
+
+- [[https://www.w3.org/TR/generic-sensor/][Generic sensor API]]
+- [[https://developer.mozilla.org/en-US/docs/Web/API/Sensor_APIs][MDN Sensor API]]
+- [[Generic sensor demos (Intel)]]
+
+** What works on my phone
+
+- Accelerometer (x, y, z)
+- Linear Acceleration (x, y, z)
+- Magnetometer (x, y, z)
+- Absolute orientation (quaternion x, y, z, w)
+  - physical orientation in relation to the Earth's reference
+    coordinate system
+  - 'accelerometer', 'gyroscope', and 'magnetometer'