Moved documentation to docs, recreated a simple README.txt, fixed build

docs/README-cmake.md

@@ -0,0 +1,31 @@
+CMake
+================================================================================
+(www.cmake.org)
+
+SDL's build system was traditionally based on autotools. Over time, this
+approach has suffered from several issues across the different supported 
+platforms.
+To solve these problems, a new build system based on CMake is under development.
+It works in parallel to the legacy system, so users can experiment with it
+without complication.
+While still experimental, the build system should be usable on the following
+platforms:
+    
+    * FreeBSD
+    * Linux
+    * VS.NET 2010
+    * MinGW and Msys
+    * OS X with support for XCode
+    
+================================================================================
+Usage
+================================================================================
+
+Assuming the source for SDL is located at ~/sdl
+
+cd ~
+mkdir build
+cd build
+cmake ../sdl
+
+This will build the static and dynamic versions of SDL in the ~/build directory.