Fix README example

[owen-c]

I couldn't find any way a custom Experiment can take a block into initialize, so I don't think this example is correct.

[franzliedke]

Maybe there's a tap missing?

Suggested change

	experiment = MyExperiment.new("various-ways")
	experiment.try("first-way") { ... }
	experiment.try("second-way") { ... }
	experiment = MyExperiment.new("various-ways").tap do |e|
	e.try("first-way") { ... }
	e.try("second-way") { ... }
	end