Document livereload usage in config file

middleman-core/lib/middleman-core/templates/shared/config.tt

@@ -40,6 +40,11 @@
 # Automatic image dimensions on image_tag helper
 # activate :automatic_image_sizes
 
+# Enable middleman-livereload
+# First: gem install middleman-livereload
+# Or add it to your Gemfile and run bundle install (preferred)
+# activate :livereload
+
 # Methods defined in the helpers block are available in templates
 # helpers do
 #   def some_helper
@@ -89,4 +94,4 @@ configure :build do
 
   # Or use a different image path
   # set :http_path, "/Content/images/"
-end
+end