Assorted delegate_missing_to doc fixes

* Fix rdoc code formatting — `tt`, not backticks

* Fix/simplify sentence grammar — should at least just be “and the like”, not “likes”, but this is just general tightening up.

* Add note that delegated methods must be public.  Tested here: https://github.com/rails/rails/blob/7ff5ccae94ce2aff76b5f8a31a28e305a047d642/activesupport/test/core_ext/module_test.rb#L359-L365

* Simplify example code for delegate_missing_to. The example had complexity that wasn’t necessary for demonstrating `delegate_missing_to`.  This gets rid of a bunch of cruft so the example is more obvious about what’s going on regarding the feature itself.

[ci skip]

1 files changed, 17 insertions, 22 deletions

diff --git a/activesupport/lib/active_support/core_ext/module/delegation.rb b/activesupport/lib/active_support/core_ext/module/delegation.rb
index 85ab739095..13f3894e6c 100644
--- a/activesupport/lib/active_support/core_ext/module/delegation.rb
+++ b/activesupport/lib/active_support/core_ext/module/delegation.rb
@@ -219,48 +219,43 @@ class Module
   # When building decorators, a common pattern may emerge:
   #
   #   class Partition
-  #     def initialize(first_event)
-  #       @events = [ first_event ]
+  #     def initialize(event)
+  #       @event = event
   #     end
   #
-  #     def people
-  #       if @events.first.detail.people.any?
-  #         @events.collect { |e| Array(e.detail.people) }.flatten.uniq
-  #       else
-  #         @events.collect(&:creator).uniq
-  #       end
+  #     def person
+  #       @event.detail.person || @event.creator
   #     end
   #
   #     private
   #       def respond_to_missing?(name, include_private = false)
-  #         @events.respond_to?(name, include_private)
+  #         @event.respond_to?(name, include_private)
   #       end
   #
   #       def method_missing(method, *args, &block)
-  #         @events.send(method, *args, &block)
+  #         @event.send(method, *args, &block)
   #       end
   #   end
   #
-  # With `Module#delegate_missing_to`, the above is condensed to:
+  # With <tt>Module#delegate_missing_to</tt>, the above is condensed to:
   #
   #   class Partition
-  #     delegate_missing_to :@events
+  #     delegate_missing_to :@event
   #
-  #     def initialize(first_event)
-  #       @events = [ first_event ]
+  #     def initialize(event)
+  #       @event = event
   #     end
   #
-  #     def people
-  #       if @events.first.detail.people.any?
-  #         @events.collect { |e| Array(e.detail.people) }.flatten.uniq
-  #       else
-  #         @events.collect(&:creator).uniq
-  #       end
+  #     def person
+  #       @event.detail.person || @event.creator
   #     end
   #   end
   #
-  # The target can be anything callable within the object. E.g. instance
-  # variables, methods, constants and the likes.
+  # The target can be anything callable within the object, e.g. instance
+  # variables, methods, constants, etc.
+  #
+  # The delegated method must be public on the target, otherwise it will
+  # raise +NoMethodError+.
   def delegate_missing_to(target)
     target = target.to_s
     target = "self.#{target}" if DELEGATION_RESERVED_METHOD_NAMES.include?(target)