Added a comment

deployment/vagrant-common/core.rb

@@ -96,6 +96,7 @@ def provider_virtualbox(config, role)
     vb.memory = ENV.fetch('TFB_VB_MEM', 2048)
     vb.cpus = ENV.fetch('TFB_VB_CPU', 2)
 
+    # mount_options addresses issue mitchellh/vagrant#4997
     override.vm.synced_folder "../..", "/FrameworkBenchmarks", mount_options: ['fmode=777', 'dmode=777']
 
     if role.eql? "all" or role.eql? "app"