Fix changelog formatting

And add a spec to check the contributors list in the Changelog.

Author: bquorning

CHANGELOG.md

@@ -513,8 +513,8 @@ Compatibility release so users can upgrade RuboCop to 0.51.0. No new features.
 [@rspeicher]: https://github.com/rspeicher
 [@jonatas]: https://github.com/jonatas
 [@pocke]: https://github.com/pocke
-[@bmorrall]: https:/github.com/bmorrall
-[@zverok]: https:/github.com/zverok
+[@bmorrall]: https://github.com/bmorrall
+[@zverok]: https://github.com/zverok
 [@timrogers]: https://github.com/timrogers
 [@yevhene]: https://github.com/yevhene
 [@walf443]: https://github.com/walf443
@@ -559,7 +559,6 @@ Compatibility release so users can upgrade RuboCop to 0.51.0. No new features.
 [@andrykonchin]: https://github.com/andrykonchin
 [@harrylewis]: https://github.com/harrylewis
 [@elliterate]: https://github.com/elliterate
-[@mlarraz]: https://github.com/mlarraz
 [@jtannas]: https://github.com/jtannas
 [@mockdeep]: https://github.com/mockdeep
 [@biinari]: https://github.com/biinari

spec/project/changelog_spec.rb

@@ -10,6 +10,22 @@
     end
   end
 
+  describe 'contributors' do
+    let(:contributors) do
+      changelog.partition("<!-- Contributors -->\n\n").last.lines
+    end
+
+    it 'does not contain duplicates' do
+      expect(contributors.uniq).to eq(contributors)
+    end
+
+    it 'links to github profiles' do
+      expect(contributors).to all(
+        match(%r{\A\[@([^\]]+)\]: https://github.com/\1\n\z})
+      )
+    end
+  end
+
   describe 'entry' do
     subject(:entries) { lines.grep(/^\*/).map(&:chomp) }