Rename 'generate' task to 'build'

Use 'rake build' to generate site, similar to 'jekyll build'.

Author: stomar

README.md

@@ -61,7 +61,7 @@ your commits and PRs should look like.
 Generate the website with
 
 ``` sh
-bundle exec rake generate
+bundle exec rake build
 ```
 
 Then start a local web server with

Rakefile

@@ -13,10 +13,10 @@ end
 HOST = 'www.ruby-lang.org'
 LANGUAGES = %w[bg de en es fr id it ja ko pl pt ru tr vi zh_cn zh_tw]
 
-task :default => [:generate]
+task :default => [:build]
 
-desc "Generates the Jekyll site"
-task :generate do
+desc "Build the Jekyll site"
+task :build do
   require 'jekyll'
   # workaround for LANG=C environment
   module Jekyll::Convertible
@@ -29,6 +29,11 @@ task :generate do
   Jekyll::Site.new(options).process
 end
 
+task :generate do
+  warn "Warning: The `generate' task is deprecated, use `build' instead."
+  Rake::Task[:build].invoke
+end
+
 desc "Serves the Jekyll site locally"
 task :serve do
   sh "rackup config.ru"
@@ -209,7 +214,7 @@ namespace :check do
   end
 
   desc 'validate _site markup with validate-website'
-  task :markup => :generate do
+  task :markup => :build do
     require 'jekyll'
     options = Jekyll.configuration
     Dir.chdir('_site') do