Fix inconsistencies in Flexvolume docs (#9706)

* Fix inconsistencies in Flexvolume docs

* remove code highlighting for Flexvolume and CSI

content/en/docs/concepts/storage/persistent-volumes.md

@@ -247,7 +247,7 @@ uses the PVC before the expansion can complete.
 * AzureFile
 * AzureDisk
 * FC (Fibre Channel)
-* FlexVolume
+* Flexvolume
 * Flocker
 * NFS
 * iSCSI
@@ -331,7 +331,7 @@ In the CLI, the access modes are abbreviated to:
 | CephFS               | ✓     | ✓    | ✓     |
 | Cinder               | ✓     | -           | -            |
 | FC                   | ✓     | ✓    | -            |
-| FlexVolume           | ✓     | ✓    | -            |
+| Flexvolume           | ✓     | ✓    | -            |
 | Flocker              | ✓     | -           | -            |
 | GCEPersistentDisk    | ✓     | ✓    | -            |
 | Glusterfs            | ✓     | ✓    | ✓     |

content/en/docs/concepts/storage/storage-classes.md

@@ -70,7 +70,7 @@ for provisioning PVs. This field must be specified.
 | CephFS               | -                   | -                                    |
 | Cinder               | ✓            | [OpenStack Cinder](#openstack-cinder)|
 | FC                   | -                   | -                                    |
-| FlexVolume           | -                   | -                                    |
+| Flexvolume           | -                   | -                                    |
 | Flocker              | ✓            | -                                    |
 | GCEPersistentDisk    | ✓            | [GCE](#gce)                          |
 | Glusterfs            | ✓            | [Glusterfs](#glusterfs)              |

content/en/docs/concepts/storage/volumes.md

@@ -1120,17 +1120,17 @@ specification, and to select the type of media to use, for clusters that have
 several media types.
 
 ## Out-of-Tree Volume Plugins
-The Out-of-tree volume plugins include the Container Storage Interface (`CSI`)
-and `FlexVolume`. They enable storage vendors to create custom storage plugins
+The Out-of-tree volume plugins include the Container Storage Interface (CSI)
+and Flexvolume. They enable storage vendors to create custom storage plugins
 without adding them to the Kubernetes repository. 
 
-Before the introduction of `CSI` and `FlexVolume`, all volume plugins (like
+Before the introduction of CSI and Flexvolume, all volume plugins (like
 volume types listed above) were "in-tree" meaning they were built, linked,
 compiled, and shipped with the core Kubernetes binaries and extend the core
 Kubernetes API. This meant that adding a new storage system to Kubernetes (a
 volume plugin) required checking code into the core Kubernetes code repository.
 
-Both `CSI` and `FlexVolume` allow volume plugins to be developed independent of
+Both CSI and Flexvolume allow volume plugins to be developed independent of
 the Kubernetes code base, and deployed (installed) on Kubernetes clusters as
 extensions.
 
@@ -1224,14 +1224,14 @@ Kubernetes component using the following feature gate flags:
 Learn how to 
 [setup your PV/PVC with raw block volume support](/docs/concepts/storage/persistent-volumes/#raw-block-volume-support).
 
-### FlexVolume
+### Flexvolume
 
-`FlexVolume` is an out-of-tree plugin interface that has existed in Kubernetes
+Flexvolume is an out-of-tree plugin interface that has existed in Kubernetes
 since version 1.2 (before CSI). It uses an exec-based model to interface with
-drivers. FlexVolume driver binaries must be installed in a pre-defined volume
+drivers. Flexvolume driver binaries must be installed in a pre-defined volume
 plugin path on each node (and in some cases master).
 
-Pods interact with FlexVolume drivers through the `flexVolume` in-tree plugin.
+Pods interact with Flexvolume drivers through the `flexvolume` in-tree plugin.
 More details can be found [here](https://github.com/kubernetes/community/blob/master/contributors/devel/flexvolume.md).
 
 ## Mount propagation
@@ -1274,7 +1274,7 @@ Its values are:
    In addition, all volume mounts created by the Container will be propagated
    back to the host and to all Containers of all Pods that use the same volume.
 
-   A typical use case for this mode is a Pod with a `FlexVolume` or `CSI` driver or
+   A typical use case for this mode is a Pod with a Flexvolume or CSI driver or
    a Pod that needs to mount something on the host using a `hostPath` volume.
 
    This mode is equal to `rshared` mount propagation as described in the