Trim trailing whitespace from *.md files

Fixes the error:

    Run bin/check-changelogs ./rails
    ............F

    Offenses:

    ./rails/railties/CHANGELOG.md:4 Trailing whitespace detected.

CODE_OF_CONDUCT.md

@@ -9,4 +9,3 @@ https://rubyonrails.org/conduct
 For a history of updates, see the page history here:
 
 https://github.com/rails/website/commits/main/_pages/conduct.html
-

actionview/app/javascript/README.md

@@ -55,4 +55,4 @@ rails-ujs is released under the [MIT License](MIT-LICENSE).
 [data]: https://www.w3.org/TR/html5/dom.html#embedding-custom-non-visible-data-with-the-data-attributes "Embedding custom non-visible data with the data-* attributes"
 [validator]: https://validator.w3.org/
 [csrf]: https://api.rubyonrails.org/classes/ActionController/RequestForgeryProtection.html
-[ujsdocs]: https://github.com/rails/jquery-ujs/wiki
+[ujsdocs]: https://github.com/rails/jquery-ujs/wiki

guides/CHANGELOG.md

@@ -1,3 +1 @@
-
-
 Please check [7-0-stable](https://github.com/rails/rails/blob/7-0-stable/guides/CHANGELOG.md) for previous changes.

guides/source/7_1_release_notes.md

@@ -1,4 +1,3 @@
-
 **DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON https://guides.rubyonrails.org.**
 
 Ruby on Rails 7.1 Release Notes

guides/source/action_cable_overview.md

@@ -282,7 +282,7 @@ class ChatChannel < ApplicationCable::Channel
   def send_welcome_message
     broadcast_to(...)
   end
-  
+
   def track_subscription
     # ...
   end

guides/source/active_record_basics.md

@@ -288,7 +288,7 @@ user = User.find_by(name: 'David')
 user.update(name: 'Dave')
 ```
 
-This is most useful when updating several attributes at once. 
+This is most useful when updating several attributes at once.
 
 If you'd like to update several records in bulk without callbacks or
 validations, you can update the database directly using `update_all`:

guides/source/active_record_postgresql.md

@@ -501,7 +501,7 @@ irb> device.id
 => "814865cd-5a1d-4771-9306-4268f188fe9e"
 ```
 
-NOTE: `gen_random_uuid()` (from `pgcrypto`) is assumed if no `:default` option 
+NOTE: `gen_random_uuid()` (from `pgcrypto`) is assumed if no `:default` option
 was passed to `create_table`.
 
 To use the Rails model generator for a table using UUID as the primary key, pass
@@ -513,7 +513,7 @@ For example:
 rails generate model Device --primary-key-type=uuid kind:string
 ```
 
-When building a model with a foreign key that will reference this UUID, treat 
+When building a model with a foreign key that will reference this UUID, treat
 `uuid` as the native field type, for example:
 
 ```ruby

guides/source/maintenance_policy.md

@@ -9,7 +9,7 @@ follows, all versions, except for security releases, in `X.Y.Z`, format.
 
 --------------------------------------------------------------------------------
 
-Versioning 
+Versioning
 ------------
 
 Rails follows a shifted version of [semver](https://semver.org/):

railties/CHANGELOG.md

@@ -1,7 +1,7 @@
 *   Add ENV["SECRET_KEY_BASE_DUMMY"] for starting production environment with a generated secret base key,
     which can be used to run tasks like `assets:precompile` without making the RAILS_MASTER_KEY available
     to the build process.
-    
+
     Dockerfile layer example:
 
     ```