This patch add a section to OneView driver docs with instructions
to migrate nodes from pre-allocaiton model to dynamic allocation
model using Ironic CLI.
Change-Id: I55fb5e3f23e763ca93648bdfbebba6447281717a
Closes-Bug: 1611155
Depends-On: I940904fbbd44b595759883d944a54dd37fac5c35