Samples: intro gist

Also make the sample regression spec more subdirectory friendly

spec/samples/samples_regression_spec.rb

@@ -16,9 +16,11 @@ describe "Squib samples" do
     it "should execute #{sample} with no errors", slow: true do
       allow(Squib.logger).to receive(:warn) {}
       allow(ProgressBar).to receive(:create).and_return(Squib::DoNothing.new)
+      Dir.chdir(File.dirname(sample)) do
         load sample
       end
     end
+  end
 
   # This test could use some explanation
   # Much of the development of Squib has been sample-driven. Every time I want