Enable OVF environment transport via ISO in example

[megian]

This enables the OVF enviroment transport via ISO variable as defined
in the Open Virtualization Format Specification Version: 2.1.1.

8.1 VirtualHardwareSection
11.1 Transport media

Reference:
https://www.dmtf.org/sites/default/files/standards/documents/DSP0243_2.1.1.pdf

Test Steps

• Create a template using the OVF example
• Instantiate a VM from that template
• Check if the content is available via ISO transport

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly (N/A because it is just an example file)
• I have updated or added any documentation accordingly (N/A because it is just an example file)

[TheRealFalcon]

Thanks!