[stable/2023.1] docs: add settings for purestorage (#1351)

This is an automated cherry-pick of #635
/assign mnaser
diff --git a/doc/source/deploy/cinder.rst b/doc/source/deploy/cinder.rst
index 41a0bc2..f09fa69 100644
--- a/doc/source/deploy/cinder.rst
+++ b/doc/source/deploy/cinder.rst
@@ -7,6 +7,11 @@
 with different backend technologies, each of which might require specific
 configuration steps.
 
+Cinder can be configured with multiple backends which would all be configured
+inside of ``cinder_helm_values.conf.backends``.   The documentation below explains
+how to configure a specific backend, but you can add multiple backends by
+adding additional entries to the ``cinder_helm_values.conf.backends`` dictionary.
+
 ********
 Ceph RBD
 ********
@@ -88,6 +93,119 @@
     not necessarily to use iSCSI as the storage protocol. In this case, the
     PowerStore driver will use the storage protocol specified inside Cinder,
 
+************
+Pure Storage
+************
+
+Pure maintains a native Cinder driver that can be used to integrate with the
+Pure Storage FlashArray. To enable the Pure Storage driver for Cinder, you need
+to provide the necessary configuration settings in your Ansible inventory.
+
+In order to use Pure Storage, you'll need to have the following information
+available:
+
+Volume Driver (``volume_driver``)
+  Use ``cinder.volume.drivers.pure.PureISCSIDriver`` for iSCSI,
+  ``cinder.volume.drivers.pure.PureFCDriver`` for Fibre Channel or
+  ``cinder.volume.drivers.pure.PureNVMEDriver`` for NVME connectivity.
+
+  If using the NVME driver, specify the ``pure_nvme_transport`` value, which the
+  supported values are ``roce`` or ``tcp``.
+
+Pure API Endpoint (``san_ip``)
+  The IP address of the Pure Storage array’s management interface or a domain name
+  that resolves to that IP address.
+
+Pure API Token (``pure_api_token``)
+  A token generated by the Pure Storage array that allows the Cinder driver to
+  authenticate with the array.
+
+You can use any other configuration settings that are specific to your needs
+by referencing the `Cinder Pure Storage documentation <https://docs.openstack.org/cinder/latest/configuration/block-storage/drivers/pure-storage-driver.html>`_.
+
+.. code-block:: yaml
+
+    cinder_helm_values:
+      storage: pure
+      pod:
+        useHostNetwork:
+          volume: true
+          backup: true
+        security_context:
+          cinder_volume:
+            container:
+              cinder_volume:
+                readOnlyRootFilesystem: true
+                privileged: true
+          cinder_backup:
+            container:
+              cinder_backup:
+                privileged: true
+      dependencies:
+        static:
+          api:
+            jobs:
+              - cinder-db-sync
+              - cinder-ks-user
+              - cinder-ks-endpoints
+              - cinder-rabbit-init
+          backup:
+            jobs:
+              - cinder-db-sync
+              - cinder-ks-user
+              - cinder-ks-endpoints
+              - cinder-rabbit-init
+          scheduler:
+            jobs:
+              - cinder-db-sync
+              - cinder-ks-user
+              - cinder-ks-endpoints
+              - cinder-rabbit-init
+          volume:
+            jobs:
+              - cinder-db-sync
+              - cinder-ks-user
+              - cinder-ks-endpoints
+              - cinder-rabbit-init
+          volume_usage_audit:
+            jobs:
+              - cinder-db-sync
+              - cinder-ks-user
+              - cinder-ks-endpoints
+              - cinder-rabbit-init
+      conf:
+        enable_iscsi: true
+        cinder:
+          DEFAULT:
+            default_volume_type: purestorage
+            enabled_backends: purestorage
+        backends:
+          rbd1: null
+          purestorage:
+            volume_backend_name: purestorage
+            volume_driver: <FILL IN>
+            san_ip: <FILL IN>
+            pure_api_token: <FILL IN>
+            # pure_nvme_transport:
+            use_multipath_for_image_xfer: true
+            pure_eradicate_on_delete: true
+      manifests:
+        deployment_backup: false
+        job_backup_storage_init: false
+        job_storage_init: false
+
+    nova_helm_values:
+      conf:
+        enable_iscsi: true
+
+.. admonition:: About ``conf.enable_iscsi``
+    :class: info
+
+    The ``enable_iscsi`` setting is required to allow the Nova instances to
+    expose volumes by making the `/dev` devices available to the containers,
+    not necessarily to use iSCSI as the storage protocol. In this case, the
+    Cinder instances will use the volume driver specified in ``volume_driver``.
+
 ********
 StorPool
 ********