Update Readme for prebuild (microsoft#48)

* Update Readme for prebuild

- Remove prerequisite for napa installation since we support pre-build.

* Refine the installation section in README

README.md

@@ -6,29 +6,12 @@
 # Napa.js
 Napa.js is a multi-threaded JavaScript runtime built on [V8](https://github.com/v8/v8), which was originally designed to develop highly iterative services with non-compromised performance in Bing. As it evolves, we find it useful to complement [Node.js](https://nodejs.org) in CPU-bound tasks, with the capability of executing JavaScript in multiple V8 isolates and communicating between them. Napa.js is exposed as a Node.js module, while it can also be embedded in a host process without Node.js dependency.
 
-## Supported OS and Compilers
-Napa.js requires C++ compiler that supports [C++14](https://en.wikipedia.org/wiki/C%2B%2B14), currently we have tested following OS/compiler combinations: 
-* Windows: 7+ with VC 2015+ (MSVC14.0+)
-* Linux: Ubuntu 14.04 LTS, 16.04 TLS, with gcc 5.4+ 
-* OSX: 10.11 (Yosemite), Apple LLVM 7.0.2 (clang-700.1.18)
-
 ## Installation
-### Prerequisites
-* Install C++ compilers that support C++14:
-    * Windows: Visual C++ Build Tools [2015](http://landinghub.visualstudio.com/visual-cpp-build-tools) / [2017](https://www.visualstudio.com/downloads/#build-tools-for-visual-studio-2017), or [Visual Studio](https://www.visualstudio.com/vs/cplusplus/)
-    * Linux: [via Apt-get](https://askubuntu.com/questions/618474/how-to-install-the-latest-gcurrently-5-1-in-ubuntucurrently-14-04)
-    * OSX: `xcode-select --install`
-* Install CMake: 
-    * Linux: [via Apt-get](https://askubuntu.com/questions/355565/how-to-install-latest-cmake-version-in-linux-ubuntu-from-command-line)
-    * OSX: [via brew](http://macappstore.org/cmake/)
-    * [Download or build](https://cmake.org/install/)
-* Install cmake-js: `npm install -g cmake-js`
-
-### Install Napa.js
+Install the latest stable version:
 ```
 npm install napajs
 ```
-\* *You can also [build Napa.js from source](https://github.com/Microsoft/napajs/wiki/build-napa.js-from-source).*
+Other options can be found in [Build Napa.js](https://github.com/Microsoft/napajs/wiki/build-napa.js).
 
 ## Quick Start
 ```js