Two things here:
1. The API guide was missing the hyper-v driver which supports
the suspend operation. Rather than hard-code a list of supported
drivers in the doc, this change just links to the entry in the
feature support matrix.
2. The supported hypervisors mention in the API reference is removed
because the end user using the API should not need to know or care
what backend hypervisor on which their server is running. They can
either suspend or not, but we don't need to mention the supporting
drivers for that in the API reference.
Change-Id: Ib76779a8e34b2c68b0f4af190f71576180360d0f
Related-Bug: #1815403
2d91a8463f