Extract doc tasks to a individual file

Rakefile

 require 'rake/clean'
 require 'rubygems/tasks'
-require 'yard'
-require 'rdoc/task'
 
 task :default => :test
 
-task :doc => 'doc:default'
-
-namespace :doc do
-  task :default => [:yard, :rdoc]
-
-  YARD::Rake::YardocTask.new
-  Rake::RDocTask.new do |rdoc|
-    rdoc.rdoc_files.include %w[
-      lib/**/*.rb
-      README.adoc
-      CHANGELOG.adoc
-      MIT-LICENSE
-      docs/**/*.adoc
-      docs/**/*.md
-    ]
-  end
-
-  desc "Build man page for epubinfo command"
-  file "man/epubinfo.1" => :ronn
-
-  desc "Build HTML man page for epubinfo command"
-  file "man/epubinfo.1.html" => :ronn
-
-  task ronn: "man/epubinfo.1.ronn" do |t|
-    sh "ronn #{t.source}"
-  end
-end
-
 Gem::Tasks.new
 task :build => :clean

rakelib/doc.rake

+require 'yard'
+require 'rdoc/task'
+
+task :doc => 'doc:default'
+
+namespace :doc do
+  task :default => [:yard, :rdoc]
+
+  YARD::Rake::YardocTask.new
+  Rake::RDocTask.new do |rdoc|
+    rdoc.rdoc_files.include %w[
+      lib/**/*.rb
+      README.adoc
+      CHANGELOG.adoc
+      MIT-LICENSE
+      docs/**/*.adoc
+      docs/**/*.md
+    ]
+  end
+
+  desc "Build man page for epubinfo command"
+  file "man/epubinfo.1" => :ronn
+
+  desc "Build HTML man page for epubinfo command"
+  file "man/epubinfo.1.html" => :ronn
+
+  task ronn: "man/epubinfo.1.ronn" do |t|
+    sh "ronn #{t.source}"
+  end
+end