[DOCS] update docs (#67)

nnvm/README.md

 # NNVM: Open Compiler for AI Frameworks
-
 [![Build Status](https://travis-ci.org/dmlc/nnvm.svg?branch=master)](https://travis-ci.org/dmlc/nnvm)
 [![GitHub license](http://dmlc.github.io/img/apache2.svg)](./LICENSE)
 
+[Installation](docs/how_to/install.md) |
+[Documentation](http://nnvm.tvmlang.org) |
+[Tutorials](http://nnvm.tvmlang.org/tutorials/index.html) |
+[Release Notes](NEWS.md)
+
 NNVM compiler offers reusable computation graph optimization and compilation for deep learning systems.
 It is backed by the [TVM stack](http://tvmlang.org) and provides modules to:
 
@@ -49,6 +53,12 @@ rmodule.set_input(**params)
 rmodule.run()
 ```
 
-## Links
+License
+-------
+Licensed under an [Apache-2.0](https://github.com/dmlc/tvm/blob/master/LICENSE) license.
+
+
+Links
+-----
 - [TinyFlow](https://github.com/tqchen/tinyflow) on how you can use  NNVM to build a TensorFlow like API.
 - [Apache MXNet](http://mxnet.io/) uses NNVM as a backend.

nnvm/docs/index.rst

 NNVM Documentation
 ==================
-
+This is a document about NNVM and NNVM compiler.
 
 Contents
 --------
@@ -9,11 +9,11 @@ Contents
    :maxdepth: 1
 
    self
-   top
    how_to/install
    tutorials/index
+   top
+   json_spec
    how_to/contribute
    how_to/deploy
-   json_spec
    api/python/index
    dev/index