Better docs on Future.

Author: jdantonio

lib/concurrent/future.rb

@@ -94,6 +94,12 @@ def execute
     #
     # @yield the asynchronous operation to perform
     #
+    # @param [Hash] opts the options controlling how the future will be processed
+    # @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