Added instructions for how to build the examples.

Rakefile

@@ -102,6 +102,7 @@ task :examples do
   require 'lib/compass'
   require 'lib/compass/exec'
   FileList['examples/*'].each do |example|
+    next unless File.directory?(example)
     puts "\nCompiling #{example}"
     puts "=" * "Compiling #{example}".length
     # compile any haml templates to html

examples/README.markdown

@@ -0,0 +1,4 @@
+To build the examples:
+
+1. You can run the compass command line from any particular compass example project
+2. You can compile them all by running `rake examples` at the top of the project directory.