Update readme (#17)

* Simple README

* Update README

* Update

Author: martinRenou

README.md

@@ -2,4 +2,44 @@
 
 Plugin to bqplot powered by WebGL.
 
-**This is an early draft and shouldn't be used yet.**
+## Requirements
+
+You need bqplot 0.13
+
+```bash
+pip install --pre bqplot
+```
+
+## Usage
+
+bqplot-gl provides marks that make use of WebGL for the rendering, providing better performances.
+
+Those marks have the same APIs as their equivalent in bqplot.
+
+```python
+from bqplot import *
+from bqplot_gl import LinesGL, ScatterGL
+
+import numpy as np
+import pandas as pd
+
+n_points = 150_000
+
+np.random.seed(0)
+y = np.cumsum(np.random.randn(n_points)) + 100.
+
+sc_x = LinearScale()
+sc_y = LinearScale()
+
+scatter = ScatterGL(
+    x=np.arange(len(y)), y=y,
+    default_size=1,
+    scales={'x': sc_x, 'y': sc_y}
+)
+ax_x = Axis(scale=sc_x, label='Index')
+ax_y = Axis(scale=sc_y, orientation='vertical', label='Points')
+
+Figure(marks=[scatter], axes=[ax_x, ax_y], title='Scatter powered by WebGL')
+```
+
+[bqplot-gl](https://github.com/bqplot/bqplot-gl/assets/21197331/55b88909-3120-41b6-a3ad-494850407bc7)