Include elasticsearch-xpack changes in CHANGELOG as part of update_ve…

…rson rake task

Rakefile

@@ -142,6 +142,7 @@ task :update_version, :old, :new do |task, args|
   log_entries[:api] = log.select { |l| l =~ /\[API\]/ }
   log_entries[:dsl] = log.select { |l| l =~ /\[DSL\]/ }
   log_entries[:ext] = log.select { |l| l =~ /\[EXT\]/ }
+  log_entries[:xpack] = log.select { |l| l =~ /\[XPACK\]/ }
 
   changelog = File.read(File.open('CHANGELOG.md', 'r'))
 
@@ -187,6 +188,15 @@ task :update_version, :old, :new do |task, args|
     changelog_update << "\n\n"
   end
 
+  unless log_entries[:xpack].empty?
+    changelog_update << "## XPACK:#{args[:new]}\n\n"
+    changelog_update << log_entries[:xpack]
+                            .map { |l| l.gsub /\[XPACK\] /, '' }
+                            .map { |l| "#{l}" }
+                            .join("\n")
+    changelog_update << "\n\n"
+  end
+
   File.open('CHANGELOG.md', 'w+') { |f| f.write changelog_update and f.write changelog }
 
   puts "\n\n", "= DIFF ".ansi(:faint) + ('='*93).ansi(:faint)