CHANGELOG: add deprecation-related notices

Change-Id: Ic5bc07145bc4c9723a41c2cc02d4f33d2efab42b
Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/c/442727
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

CHANGELOG.md

@@ -117,6 +117,9 @@ allows virtual bdevs to be shut down cleanly as opposed to the
 previous behavior that didn't differentiate between hotremove and
 planned shutdown.
 
+The `delete_bdev` RPC is now deprecated. Users should instead use the specific deletion RPC
+for the bdev type to be removed (i.e. delete_malloc_bdev).
+
 ### logical volumes
 
 Logical volume bdev can now be marked as read only using `set_read_only_lvol_bdev` RPC.
@@ -157,6 +160,16 @@ multi-process device hotplug yet and continues to work the same way it always di
 
 Dropped support for DPDK 16.07 and earlier, which SPDK won't even compile with right now.
 
+### RPC
+
+The following RPC commands deprecated in the previous release are now removed:
+ - construct_virtio_user_scsi_bdev
+ - construct_virtio_pci_scsi_bdev
+ - construct_virtio_user_blk_bdev
+ - construct_virtio_pci_blk_bdev
+ - remove_virtio_scsi_bdev
+ - construct_nvmf_subsystem
+
 ## v18.10:
 
 ### nvme