Remove expiremental note in the VGPU docs
Remove expiremental note in the VGPU docs

FWIW, we already say in the feature classification documentation that the
feature is experimental [1] but we also now have functional tests that help
to verify that the feature is working.
I think we can just remove the note about this then.

[1] https://docs.openstack.org/nova/latest/user/feature-classification.html#operation_virtual_gpu

Change-Id: I705b3aeb1da33ddc41d4306ad91ad7cb70fcf4e4

mahak/nova,openstack/nova,klmitch/nova,klmitch/nova,klmitch/nova,rahulunair/nova,mahak/nova,openstack/nova,klmitch/nova,rahulunair/nova,openstack/nova,rahulunair/nova,mahak/nova