Add CHANGELOG as vendored file (#1239)

- Searchable
- Using two_column_layout

See #1233

config.rb

@@ -7,7 +7,7 @@
 activate :syntax
 activate :i18n
 activate :search do |search|
-  search.resources = ["index.html", "guides/", "#{config[:current_version]}/", "compatibility.html", "conduct.html", "contributors.html"]
+  search.resources = ["index.html", "guides/", "#{config[:current_version]}/", "changelog.html", "compatibility.html", "conduct.html", "contributors.html"]
 
   search.index_path = "search/lunr-index.json"
 
@@ -187,6 +187,7 @@
 
 redirect "sponsors.html", to: "https://rubygems.org/pages/sponsors" # Backwards compatibility
 
+page "/changelog.html", layout: :two_column_layout
 page "/conduct.html", layout: :two_column_layout
 page "/compatibility.html", layout: :two_column_layout
 page /\/v(\d+.\d+)\/(?!bundle_|commands|docs|man)(.*)/, layout: :two_column_layout

lib/tasks/vendor_files.rake

@@ -14,6 +14,8 @@ RELATIVE_LINK_REGEX = %r{
 def new_link(file, link)
   if link.end_with?("CODE_OF_CONDUCT.md")
     "conduct" # Special case we manually write
+  elsif link.end_with?("CHANGELOG.md")
+    "changelog" # Special case we manually write
   elsif link.start_with?("mailto:") || link.start_with?("http")
     link
   else
@@ -65,5 +67,6 @@ task repo_pages: :update_vendor do
     end
 
     write_file("../CODE_OF_CONDUCT.md", File.expand_path("./conduct.html.md", source_dir))
+    write_file("../CHANGELOG.md", File.expand_path("./changelog.html.md", source_dir))
   end
 end