Document PXE with Spanning Tree in troubleshooting FAQ
Document PXE with Spanning Tree in troubleshooting FAQ

STP can cause issues with DHCP and PXE on some switches, and there is an
easy way to resolve it by change the switch port STP mode. This patch
documents the issue and the solution with an example.

Change-Id: I77aa88ec1c6d8d90e57d22365e488ecd704fe64f

NaohiroTamura/ironic,openstack/ironic,NaohiroTamura/ironic,pshchelo/ironic,openstack/ironic,SauloAislan/ironic,pshchelo/ironic,SauloAislan/ironic