Create publishdocs target for publishing

tox -e publishdocs will be called by the post jenkins jobs to prepare
everything for publishing - and then the content of publish-docs
gets copied.

Change-Id: Ic6540fd279549e082ccc0abd60623b553e798f1d
Added recommendation for reserved_host_memory_mb value

The default for reserved_host_memory_mb is 512 MB but because the
vCenter driver reports memory available to the VMs, VMware suggests
setting this value to 0 MB. Added this recommendation to the
 VMwareVCDriver configuration options section

Change-Id: I11e01ff36a4d91c2c268b2ece65b4e7e19990468
Closes-Bug: #1267303
Merge "Create publishdocs target for publishing"
Merge "Added recommendation for reserved_host_memory_mb value"