docs: add basic contents to table of contetns (#490)

docs/FAQ.md

 LightGBM FAQ
 =======================
 
-###Catalog
+### Catalog
 
 - [Python-package](FAQ.md#python-package)
 
-###Python-package
+### Python-package
 
 - **Question 1**: I see error messages like this when install from github using `python setup.py install`.
 

docs/Parameters-tuning.md

+# Parameters Tuning
+
 This is a page contains all parameters in LightGBM.
 
 ***List of other Helpful Links***

docs/Parameters.md

+# Parameters
+
 This is a page contains all parameters in LightGBM.
 
 ***List of other Helpful Links***

docs/Python-API.md

+# Python API Reference
+
 ## Catalog
 
 * [Data Structure API](Python-API.md#basic-data-structure-api)

docs/Quick-Start.md

+# Quick Start
+
 This is a quick start guide for LightGBM of cli version.
 
 Follow the [Installation Guide](./Installation-Guide.md) to install LightGBM first.

docs/index.rst

@@ -7,10 +7,21 @@ Welcome to LightGBM's documentation!
 ====================================
 
 .. toctree::
-   :maxdepth: 2
+   :maxdepth: 1
    :caption: Contents:
 
-
+   Installation Guide <https://github.com/Microsoft/LightGBM/wiki/Installation-Guide>
+   Quick Start <Quick-Start>
+   Python Quick Start <Python-intro>
+   Features <https://github.com/Microsoft/LightGBM/wiki/Features>
+   Experiments <https://github.com/Microsoft/LightGBM/wiki/Experiments>
+   Parameters <Parameters>
+   Parameters Tuning <Parameters-tuning>
+   Python API Reference <Python-API>
+   Parallel Learning Guide <https://github.com/Microsoft/LightGBM/wiki/Parallel-Learning-Guide>
+   GPU Tutorial <GPU-Tutorial>
+   FAQ <FAQ>
+   Development Guide <development>
 
 Indices and tables
 ==================