#1191 - highlight 'experimental' state of VMWare vmx.version in docs

As per the comments on the pull request It was felt that vmx hardware
version should be more explicitly documented as ‘experimental’ when
using a non default value.

website/source/docs/builders/vmware-iso.html.markdown

@@ -216,7 +216,7 @@ each category, the available options are alphabetized and described.
   `tools_upload_flavor`. By default the upload path is set to
   `{{.Flavor}}.iso`.
 
-* `version` (string) - This is the vmx hardware version for the new virtual machine, by default this is '9'.  [reference document](http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003746)
+* `version` (string) - The [vmx hardware version](http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003746) for the new virtual machine.  Only the default value has been tested, any other value is expiermental.  Default value is '9'.
 
 * `vm_name` (string) - This is the name of the VMX file for the new virtual
   machine, without the file extension. By default this is "packer-BUILDNAME",