Doc 'isolate-aggregates' has some incorrect examples

[Eric Xie]

At https://docs.openstack.org/nova/latest/reference/isolate-aggregates.html,
* command `host_id=$(openstack resource provider show <HOST1_UUID>)` can not get the uuid.
* command `traits=$(openstack --os-placement-api-version 1.6 resource provider trait list -f value $server_id | sed 's/^/--trait /')` uses 'server_id' not 'host_id'.

# git log
commit ab6834145f3fe1d33ce7f292727a6bc2be50efd9 (HEAD -> stable/train, origin/stable/train)
Merge: 66585e8af1 821506a50c
Author: Zuul <email address hidden>
Date: Mon Oct 21 18:50:20 2019 +0000

    Merge "Fix exception translation when creating volume" into stable/train

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/695832

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/695832
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=0195939588da595868d20d4185af77ee4a2debd5
Submitter: Zuul
Branch: master

commit 0195939588da595868d20d4185af77ee4a2debd5
Author: ericxiett <[e-mail]>
Date: Mon Nov 25 00:40:00 2019 +0000

    Fix incorrect command examples

    The command of 'openstack resource provider show <HOST1_UUID>' does not
    return the uuid. This patch fixes it. Then following commands use
    'host_id' instead of 'server_id'.

    Change-Id: I60298ea3b22d9dfec2cd7a3e9950ed04aedc6bf5
    Closes-Bug: #1853745