Add a project spec for future changelog entry

Follow up rubocop/rubocop#10991.

Author: koic

CONTRIBUTING.md

@@ -51,7 +51,6 @@ Here are a few examples:
 
 ```
 * [#67](https://github.com/rubocop/rubocop-rails/issues/67): Fix an incorrect autocorrect for `Rails/TimeZone` when using `DateTime`. ([@koic][])
-* New cop `ElseLayout` checks for odd arrangement of code in the `else` branch of a conditional expression. ([@bbatsov][])
 ```
 
 * Create one file `changelog/{type}_{some_description}.md`, where `type` is `new` (New feature), `fix` or `change`, and `some_description` is unique to avoid conflicts. Task `changelog:fix` (or `:new` or `:change`) can help you.

spec/project_spec.rb

@@ -215,6 +215,13 @@
 
           include_examples 'has Changelog format'
 
+          it 'has a link to the issue or pull request address at the beginning' do
+            repo = 'rubocop/rubocop-rails'
+            address_pattern = %r{\A\* \[#\d+\]\(https://github\.com/#{repo}/(issues|pull)/\d+\):}
+
+            expect(entries).to all(match(address_pattern))
+          end
+
           it 'has a link to the contributors at the end' do
             expect(entries).to all(match(/\(\[@\S+\]\[\](?:, \[@\S+\]\[\])*\)$/))
           end