website/docs: document Vagrantfile updates

.gitignore

@@ -6,6 +6,7 @@ acceptance_config.yml
 boxes/*
 /Vagrantfile
 /.vagrant
+/website/docs/.vagrant
 /website/www/.vagrant
 /vagrant-spec.config.rb
 

website/docs/source/v2/vagrantfile/machine_settings.html.md

@@ -18,8 +18,16 @@ for the machine to boot and be accessible. By default this is 300 seconds.
 <hr>
 
 `config.vm.box` - This configures what [box](/v2/boxes.html) the
-machine will be brought up against. The value here should match one of
-the installed boxes on the system.
+machine will be brought up against. The value here should be the name
+of an installed box or a shorthand name of a box in
+[Vagrant Cloud](#).
+
+<hr>
+
+`config.vm.box_check_update` - If true, Vagrant will check for updates to
+the configured box on every `vagrant up`. If an update is found, Vagrant
+will tell the user. By default this is false, and updates must be explicitly
+checked for using `vagrant box outdated`.
 
 <hr>
 
@@ -53,8 +61,10 @@ URL, then SSL certs will be verified.
 <hr>
 
 `config.vm.box_url` - The URL that the configured box can be found at.
-If the box is not installed on the system, it will be retrieved from this
-URL when `vagrant up` is run.
+If `config.vm.box` is a shorthand to a box in [Vagrant Cloud](#)
+then this value doesn't need to be specified. Otherwise, it should
+point to the proper place where the box can be found if it isn't
+installed.
 
 This can also be an array of multiple URLs. The URLs will be tried in
 order. Note that any client certificates, insecure download settings, and
@@ -62,6 +72,14 @@ so on will apply to all URLs in this list.
 
 <hr>
 
+`config.vm.box_version` - The version of the box to use. This defaults to
+">= 0" (the latest version available). This can contain an arbitrary list
+of constraints, separated by commas, such as: `>= 1.0, < 1.5`. When constraints
+are given, Vagrant will use the latest available box satisfying these
+constraints.
+
+<hr>
+
 `config.vm.graceful_halt_timeout` - The time in seconds that Vagrant will
 wait for the machine to gracefully halt when `vagrant halt` is called.
 Defaults to 300 seconds.