[DOC]Add create_share_from_snapshot_support extra spec

[OpenStack Infra]

https://review.openstack.org/356682
Dear bug triager. This bug was created since a commit was marked with DOCIMPACT.
Your project "openstack/manila" is set up so that we directly report the documentation bugs against it. If this needs changing, the docimpact-group option needs to be added for the project. You can ask the OpenStack infra team (#openstack-infra on freenode) for help if you need to.

commit 0d6db3588c212a7d121bb5d95ea0a82b034490a1
Author: Clinton Knight <email address hidden>
Date: Tue Aug 16 22:36:13 2016 -0400

    Add create_share_from_snapshot_support extra spec

    The snapshot_support extra spec has always meant two
    things: a driver can take snapshots and create shares
    from snapshots. As we add alternate snapshot semantics,
    it is likely that some drivers will want to support
    snapshots and some of the new semantics while being
    unable to create new shares from snapshots.

    This work adds a new extra spec,
    create_share_from_snapshot_support, that removes the
    overloading on snapshot_support. It also makes the
    existing snapshot_support extra spec optional,
    allowing admins to create types without setting
    snapshot_support; shares created with such types
    will not support snapshots.

    APIImpact
    DocImpact

    Co-Authored-By: Goutham Pacha Ravi <email address hidden>
    Implements: blueprint add-create-share-from-snapshot-extra-spec
    Change-Id: Ib0ad5fbfdf6297665c208149b08c8d21b3c232be

[Tom Barron (tpb)]

Let's assign this one to Goutham since he was a co-author of the create from snapshot spec. He can close this out if the doc work for this is completed.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/745291

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/745291
Committed: https://git.openstack.org/cgit/openstack/manila/commit/?id=bce5429d1ac89a26110f4221179a6fcef736107a
Submitter: Zuul
Branch: master

commit bce5429d1ac89a26110f4221179a6fcef736107a
Author: Goutham Pacha Ravi <email address hidden>
Date: Thu Aug 6 23:39:37 2020 -0700

    Update "Create and manage shares" doc

    This is the basic user guide for manila:

    - Update examples and outputs
    - Add limits and metadata examples
    - Add descriptions about common concepts
      including share type extra specifications
    - Add contents for easy navigation

    Change-Id: Idf374866a63e0da2c4af3157ac5f471af6173d5e
    Closes-Bug: #1652375
    Signed-off-by: Goutham Pacha Ravi <email address hidden>