Add build overview docs

docs/builds.rst

@@ -1,8 +1,34 @@
 Building Dust3D
 -------------------
 
-Windows
-=======
+Overview
+==========
+The core mesh algorithms of Dust3D written in Rust language, located in meshlite repository,
+
+    https://github.com/huxingyi/meshlite
+
+The UI of Dust3D built in Qt5, the only thirdparty dependency is CGAL library, however, CGAL will introduce some new dependencies, such as boost and gmp library.
+
+Prerequisites
+===============
+* CGAL
+
+    https://www.cgal.org/
+
+* Rust
+
+    https://www.rust-lang.org/en-US/install.html
+
+
+Building
+==========
+
+Here is the snapshot of the command line of one build, you may use different defines on your system. If you encounter build issues, please follow the ci files step by step,
+
+    https://github.com/huxingyi/dust3d/blob/master/appveyor.yml
+    https://github.com/huxingyi/dust3d/blob/master/.travis.yml
+
+* Windows
 
 .. code-block:: none
 
@@ -11,8 +37,7 @@ Windows
     C:\Users\IEUser\Desktop\dust3d>qmake DEFINES+=BOOST_INCLUDEDIR=C:\dev\boost_1_55_0\boost_1_55_0 DEFINES+=CGAL_DIR=C:\dev\CGAL-4.11.1
     C:\Users\IEUser\Desktop\dust3d>nmake -f Makefile.Release
 
-Mac
-=======
+* Mac
 
 .. code-block:: sh