Add info.rb to gemspec

Author: ima1zumi

irb.gemspec

@@ -32,6 +32,7 @@ Gem::Specification.new do |spec|
     "lib/irb/cmd/chws.rb",
     "lib/irb/cmd/fork.rb",
     "lib/irb/cmd/help.rb",
+    "lib/irb/cmd/info.rb",
     "lib/irb/cmd/load.rb",
     "lib/irb/cmd/measure.rb",
     "lib/irb/cmd/nop.rb",