Minor documentation updates to Future.

Author: jdantonio

lib/concurrent/future.rb

@@ -51,6 +51,8 @@ class Future < IVar
     # @option opts [Boolean] :operation (false) when +true+ will execute the future on the global
     #   operation pool (for long-running operations), when +false+ will execute the future on the
     #   global task pool (for short-running tasks)
+    # @option opts [object] :executor when provided will run all operations on
+    #   this executor rather than the global thread pool (overrides :operation)
     # @option opts [String] :dup_on_deref (false) call +#dup+ before returning the data
     # @option opts [String] :freeze_on_deref (false) call +#freeze+ before returning the data
     # @option opts [String] :copy_on_deref (nil) call the given +Proc+ passing the internal value and

spec/concurrent/future_spec.rb

@@ -8,6 +8,7 @@ module Concurrent
 
     let!(:value) { 10 }
     let(:executor) { PerThreadExecutor.new }
+
     subject do
       Future.new(executor: executor){
         value