Added Rackspace Extensions.

README.asciidoc

@@ -0,0 +1,20 @@
+= Rackspace Extensions to the OpenStack Compute API
+
+== Building the Docs
+
+You will need the latest version of
+http://maven.apache.org/download.html[Maven 3] to build the
+documentation.
+
+Simply type:
+
+----
+mvn clean install
+----
+
+After the build you should find a PDFs in
++target/docbkx/pdf/+ and a web versions in
++target/docbkx/webhelp/+.
+
+The web version contains a copy of the PDF, so you need only deploy
+this version.