Add demo

docs/_static/demo.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+git clone https://github.com/microsoft/qlib.git
+cd qlib
+ls
+pip install pyqlib
+# or
+# pip install numpy
+# pip install --upgrade cython
+# python setup.py install
+cd examples
+ls
+qrun benchmarks/LightGBM/workflow_config_lightgbm_Alpha158.yaml