docs: Add logical storage pool overwrite change description to news.xml
docs: Add logical storage pool overwrite change description to news.xml

Add "New Features" entry to describe the overwrite flag for logical backend.

andreabolognani/libvirt,jardasgit/libvirt,taget/libvirt,nertpinx/libvirt,nertpinx/libvirt,jfehlig/libvirt,olafhering/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,datto/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,jfehlig/libvirt,zippy2/libvirt,nertpinx/libvirt,taget/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,crobinso/libvirt,eskultety/libvirt,datto/libvirt,VenkatDatta/libvirt,jfehlig/libvirt,olafhering/libvirt,zippy2/libvirt,taget/libvirt,crobinso/libvirt,VenkatDatta/libvirt,crobinso/libvirt,fabianfreyer/libvirt,libvirt/libvirt,libvirt/libvirt,fabianfreyer/libvirt,datto/libvirt,eskultety/libvirt,jardasgit/libvirt,eskultety/libvirt,olafhering/libvirt,crobinso/libvirt,libvirt/libvirt,jardasgit/libvirt,taget/libvirt,jfehlig/libvirt,nertpinx/libvirt,jardasgit/libvirt,andreabolognani/libvirt,datto/libvirt,eskultety/libvirt,taget/libvirt,zippy2/libvirt,eskultety/libvirt,andreabolognani/libvirt,zippy2/libvirt,olafhering/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,VenkatDatta/libvirt,VenkatDatta/libvirt,libvirt/libvirt,datto/libvirt