add example and readme

examples/python-guide/simple_example.py

+import numpy as np
+import random
+import lightgbm as lgb
+from sklearn import datasets, metrics, model_selection
+
+rng = np.random.RandomState(2016)
+
+X, y = datasets.make_classification(n_samples=10000, n_features=100)
+x_train, x_test, y_train, y_test = model_selection.train_test_split(X, y, test_size=0.1, random_state=1)
+lgb_model = lgb.LGBMClassifier(n_estimators=100).fit(x_train, y_train, [(x_test, y_test)], eval_metric="auc")

python-package/README.rst

+LightGBM Python Package
+=======================
+
+Installation
+------------
+
+1. Following `Installation Guide <https://github.com/Microsoft/LightGBM/wiki/Installation-Guide>`__ to build first.
+   For the windows user, please change the build config to ``DLL``.
+2. Install with ``cd python-package; python setpy.py install`` 
+
+Note: Make sure you have `setuptools <https://pypi.python.org/pypi/setuptools>`__
+
+
+
+Examples
+--------
+
+-  Refer also to the walk through examples in `python-guide
+   folder <https://github.com/Microsoft/LightGBM/tree/master/examples/python-guide>`__