Enhanced documentation for building on windows.

Todo:
1. Is ruby required on Mac OS? If yes, how to install on Mac OS?
2. Could x64 be supported in Windows? If yes, how to adapt the build system?

Author: tomwaitforitmy

README.md

@@ -1,6 +1,7 @@
 # Build Dependencies
 
 * Qt 5.7
+* Ruby (any stable version)
 * (OS X) Sparkle
 * (Windows) WinSparkle
 
@@ -16,19 +17,32 @@ brew link qt5 --force
 
 ## Windows
 
+* Install [Ruby](https://rubyinstaller.org/downloads/)
 * Install [Qt](http://qt-project.org/downloads) 
- * I use the Qt libraries for Windows VS 2013.
+ * I use the Qt libraries for Windows VS 2013. Make sure to choose 32 bit under Windows.
 * Install [WinSparkle](https://github.com/vslavik/winsparkle) 
- * Clone the repository and build the library, for example with VS 2013. The precompiled releases are ancient.
+ * Clone the repository and build the library, for example with VS 2013. The precompiled releases are ancient. Make sure to build 32 bit.
 
 # Build Instructions
 
+## Mac OS X
+
 ```
 qmake
 make
 ```
 
-(Use ``nmake`` instead of ``make`` on Windows)
+## Windows
+
+* Add Qt, VS 2013 and WinSparkle to your system path.
+* Initialize the environment variables:
+ * call qtenv2.bat (default location: ..\Qt\5.5\msvc2013\bin\qtenv2.bat)
+ * call vcvarsall.bat (default location: ..\VS2013\VC\vcvarsall.bat)
+
+```
+qmake
+nmake
+```
 
 The resulting binary can be found in the ``build`` subfolder.