Merge pull request #57 from thewtex/readme-update

Readme update

README.md

@@ -0,0 +1,29 @@
+# CastXML Superbuild
+
+[![CI](https://github.com/CastXML/CastXMLSuperbuild/actions/workflows/ci.yml/badge.svg)](https://github.com/CastXML/CastXMLSuperbuild/actions/workflows/ci.yml)
+
+This builds [CastXML](https://github.com/CastXML/CastXML) and its
+dependencies (LLVM/Clang) with CMake\'s
+[ExternalProject](http://www.cmake.org/cmake/help/git-master/module/ExternalProject.html)
+module. It is a cross-platform way to build CastXML.
+
+This can be built like any other [CMake](http://cmake.org) project. For
+example:
+
+    git clone https://github.com/CastXML/CastXMLSuperbuild.git
+    mkdir CastXMLSuperbuild-build
+    cd CastXMLSuperbuild-build
+    cmake -GNinja ../CastXMLSuperbuild
+    ninja
+
+This requires [ninja](https://ninja-build.org/), which comes with recent
+Visual Studio on Windows, can be installed on macOS with `brew install ninja`,
+and can be installed with the `ninja-build` package in most Linux package
+managers.
+
+The resulting [castxml]{.title-ref} executable will be located at
+[CastXMLSuperbuild-build/castxml/bin/castxml]{.title-ref}.
+
+The resulting binary builds for Linux, Mac OSX, and Windows [are
+available
+here](https://data.kitware.com/#collection/57b5c9e58d777f126827f5a1/folder/57b5de948d777f10f2696370).