use new syntax for live reload

Rakefile

@@ -4,15 +4,15 @@ require "rake/testtask"
 
 desc "Serve the site with live reload for development"
 task :serve do
-  sh "bundle exec jekyll liveserve", verbose: false
+  sh "bundle exec jekyll serve --livereload", verbose: false
 end
 
 # This option may cause pages to not be rebuilt when an underlying data file
 # (e.g., _data/*.yml) changes. In most cases it's OK, but you may need to use
 # the 'serve' task instead if changing data files.
 desc "Serve the site with live reload for development (incremental builds)"
 task :incrementalserve do
-  sh "bundle exec jekyll liveserve --incremental", verbose: false
+  sh "bundle exec jekyll serve --livereload --incremental", verbose: false
 end
 
 desc "Build the site to the default Jekyll output directory"