Rename Flexvolume to FlexVolume in docs (#16333)

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

@@ -1205,16 +1205,16 @@ 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
+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.
 
@@ -1371,14 +1371,14 @@ provisioning/delete, attach/detach, mount/unmount and resizing of volumes.
 In-tree plugins that support CSI Migration and have a corresponding CSI driver implemented
 are listed in the "Types of Volumes" section above.
 
-### Flexvolume {#flexVolume}
+### 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/sig-storage/flexvolume.md).
 
 ## Mount propagation
@@ -1414,7 +1414,7 @@ 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