Include user guide Overview section in README.md

README.md

@@ -4,7 +4,39 @@
 
 Rscons (https://github.com/holtrop/rscons) is an open-source build system
 for developers.
+It supports the following features:
 
-Rscons is written in Ruby, and is inspired by [SCons](https://scons.org/) and [waf](https://waf.io/).
+  * multi-threaded job execution
+  * auto-configuration
+  * built-in builders for several common operations
+  * out-of-the-box support for C, C++, and D languages
+  * extensibility for other languages or custom builders
+  * compatible with Windows, Linux, OS X, and FreeBSD
+  * colorized output with build progress
+  * build hooks
+  * user-defined tasks with dependencies and custom parameters
+  * build variants
+
+At its core, Rscons is mainly an engine to:
+
+  * determine the proper order to perform build steps,
+  * determine whether each build target is up to date or in need of rebuild, and
+  * schedule those build steps across multiple threads as efficiently as possible.
+
+Along the way, Rscons provides a concise syntax for specifying common types of
+build steps, but also provides an extensible framework for performing
+custom build operations as well.
+
+Rscons takes inspiration from:
+
+  * [SCons](https://scons.org/)
+  * [waf](https://waf.io/)
+  * [rake](https://github.com/ruby/rake)
+  * [CMake](https://cmake.org/)
+  * [Autoconf](https://www.gnu.org/software/autoconf/)
+
+Rscons is written in Ruby.
+The only requirement to run Rscons is that the system has a Ruby interpreter
+installed.
 
 See [https://holtrop.github.io/rscons/index.html](https://holtrop.github.io/rscons/index.html) for User Guide and Installation instructions.