Description of problem:
The REST-API Guide [1] is missing documentation on how to enable/disable the "serial console" of a VM.

Version-Release number of selected component (if applicable):
3.6

How reproducible:
always

Steps to Reproduce:
Missing documentation in REST-API Guide [1]

Actual results:
Feature not documented in REST-API Guide [1]

Expected results:
Feature documented in REST-API Guide [1]

  Example:
  <vm>
    <console enabled="true" />
  </vm>

  The "All-Content: true" header has to be set.

  See bugzilla [2] Comment 12 for details,

Additional info:
- this downstream bugzilla refers to RHEV-M 3.6
- upstream bugzilla [2]

Links:
1) https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Virtualization/3.6/html-single/REST_API_Guide/index.html
2) https://bugzilla.redhat.com/show_bug.cgi?id=1321582