DOC: add "Precompile assets (CSS, JS, ...)"

Vagrantfile

@@ -70,6 +70,9 @@ Vagrant.configure("2") do |config|
   # INSTALL - Finalize installation (1)
   vagrant ssh -c 'cd src; bin/setup'
 
+  # Precompile assets (CSS, JS, ...)
+  vagrant ssh -c 'cd src; rails assets:precompile'
+  
   # PUMA - Start server to be able to restart it quickly (use Ctrl-C to stop it)
   vagrant ssh -c 'cd src; RAILS_QUEUE_ADAPTER=delayed_job; bin/rails server --binding=0.0.0.0'