Update README with building section

Guardfile

@@ -1,12 +1,11 @@
 require 'asciidoctor'
 require 'erb'
-require './src/main/ruby/readme.rb'
 
 options = {:mkdirs => true, :safe => :unsafe, :attributes => 'linkcss'}
 
 guard 'shell' do
   watch(/^src\/[A-Za-z].*\.adoc$/) {|m|
-    SpringCloud::Build.render_file('src/main/asciidoc/README.adoc', :to_file => './README.adoc')
+    Asciidoctor.load_file('src/main/asciidoc/README.adoc', :to_file => './README.adoc', safe: :safe, parse: false, attributes: 'allow-uri-read')
     Asciidoctor.render_file('src/main/asciidoc/spring-cloud-netflix.adoc', options.merge(:to_dir => 'target/generated-docs'))
   }
 end

docs/src/main/asciidoc/README.adoc

@@ -13,3 +13,6 @@ include::intro.adoc[]
 * External Configuration: a bridge from the Sprnig Environment to Archaius (enabls native configuration of Netflix components using Spring Boot conventions)
 * Router and Filter: automatic regsitration of Zuul filters,a nd a simple convention over configuration approach to reverse proxy creation
 
+== Building
+
+include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/src/main/asciidoc/building.adoc[]

docs/src/main/ruby/generate_readme.sh

@@ -18,7 +18,7 @@ file = ARGV[0] if ARGV.length>0
 
 srcDir = File.dirname(file)
 out = "// Do not edit this file (e.g. go instead to src/main/asciidoc)\n\n"
-doc = Asciidoctor.load_file file, safe: :safe, parse: false
+doc = Asciidoctor.load_file file, safe: :safe, parse: false, attributes: 'allow-uri-read'
 out << doc.reader.read
 
 unless options[:to_file]