Document compatibility and support status of virtualized environments in the install guide

Because so many new customers want to use virtualisation and are asking the sales/support teams about it, I would like a document our stance either in, or linked from our install guide at http://www.atlassian.com/software/jira/docs/latest/requirements.html

This will enable customers seeking to run JIRA in virtualisation/virtualization tools like VMWare to use our offical docs to find out about the supportability and compatibility of their intended setup.