Merge pull request rook#15429 from BlaineEXE/pend-release-note

doc: add obc allow list to pending release notes

PendingReleaseNotes.md

@@ -2,5 +2,14 @@
 
 ## Breaking Changes
 
+Object:
+
+- Some ObjectBucketClaim options were added in Rook v1.16 that allowed more control over buckets.
+    These controls allow users to self-serve their own S3 policies, which many administrators might
+    consider a risk, depending on their environment. Rook has taken steps to ensure potentially risky
+    configurations are disabled by default to ensure the safest off-the-shelf configurations.
+    Administrators who wish to allow users to use the full range of OBC configurations must use the
+    new `ROOK_OBC_ALLOW_ADDITIONAL_CONFIG_FIELDS` to enable users to set potentially risky options.
+    See https://github.com/rook/rook/pull/15376 for more information.
 
 ## Features