docs: ComputeDriver.update_provider_tree in nova

[Matt Riedemann]

- [x] This is a doc addition request.

The document should be updated for the reshape provider tree changes made in Stein:

https://specs.openstack.org/openstack/nova-specs/specs/stein/approved/reshape-provider-tree.html#changes-to-update-provider-tree

Specifically the method signature change, the fact that allocations can be modified, and the general reshape flow with the ReshapeNeeded exception.

-----------------------------------
Release: 18.1.0.dev629 on 2018-10-30 13:27
SHA: d1e38f06bb5282dd9bf81d979926a0ebbfd93caa
Source: https://git.openstack.org/cgit/openstack/nova/tree/doc/source/reference/update-provider-tree.rst
URL: https://docs.openstack.org/nova/latest/reference/update-provider-tree.html

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/633375

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/633375
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=9db41c5ee09f4b3d4d072282e32510f2d7fa09ab
Submitter: Zuul
Branch: master

commit 9db41c5ee09f4b3d4d072282e32510f2d7fa09ab
Author: Hesam Chobanlou <email address hidden>
Date: Sat Jan 26 19:56:17 2019 -0500

    docs: ComputeDriver.update_provider_tree in nova

    This change is an update to the nova reference documentation to reflect
    changes to the ComputeDriver.update_provider_tree method in nova drivers.

    Change-Id: Ifae98d888069477748ade7ef5e0a5cde5c88ffc2
    Closes-Bug: #1800657

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 19.0.0.0rc1 release candidate.