docs: reset pending release notes

Since 1.15 is released, we reset the pending release notes
for the 1.16 release

Signed-off-by: Travis Nielsen <tnielsen@redhat.com>

PendingReleaseNotes.md

@@ -1,28 +1,6 @@
-# v1.15 Pending Release Notes
+# v1.16 Pending Release Notes
 
 ## Breaking Changes
 
-- Rook has deprecated CSI network "holder" pods.
-    If there are pods named `csi-*plugin-holder-*` in the Rook operator namespace, see the
-    [detailed documentation](../CRDs/Cluster/network-providers.md#holder-pod-deprecation)
-    to disable them. This deprecation process is required before upgrading to the future Rook v1.16.
-- Ceph COSI driver images have been updated. This impacts existing COSI Buckets, BucketClaims, and
-    BucketAccesses. Update existing clusters following the guide
-    [here](https://github.com/rook/rook/discussions/14297).
-- During CephBlockPool updates, Rook will now return an error if an invalid device class is
-    specified. Pools with invalid device classes may start failing until the correct device class is
-    specified. For more info, see [#14057](https://github.com/rook/rook/pull/14057).
-- CephObjectStore, CephObjectStoreUser, and OBC endpoint behavior has changed when CephObjectStore
-    `spec.hosting` configurations are set. Use the new `spec.hosting.advertiseEndpoint` config to
-    define required behavior as
-    [documented](../Storage-Configuration/Object-Storage-RGW/object-storage.md#object-store-endpoint).
-- Minimum version of Kubernetes supported is increased to K8s v1.26.
 
 ## Features
-
-- Added support for Ceph Squid (v19)
-- Allow updating the device class of OSDs, if `allowDeviceClassUpdate: true` is set
-- CephObjectStore support for keystone authentication for S3 and Swift
-    (see [#9088](https://github.com/rook/rook/issues/9088)).
-- Support K8s versions v1.26 through v1.31.
-- Use fully-qualified image names (`docker.io/rook/ceph`) in operator manifests and helm charts