Fix typos for AS::Notifications::Fanout::Handle [ci-skip]

Author: jonathanhefner

activesupport/lib/active_support/notifications/fanout.rb

@@ -210,11 +210,11 @@ def groups_for(name) # :nodoc:
         groups
       end
 
-      # A +Handle+ is used to record the start and finish time of event
+      # A +Handle+ is used to record the start and finish time of event.
       #
-      # Both #start and #finish must each be called exactly once
+      # Both #start and #finish must each be called exactly once.
       #
-      # Where possible, it's best to the block form, ActiveSupport::Notifications.instrument.
+      # Where possible, it's best to use the block form: ActiveSupport::Notifications.instrument.
       # +Handle+ is a low-level API intended for cases where the block form can't be used.
       #
       #   handle = ActiveSupport::Notifications.instrumenter.build_handle("my.event", {})