doc: release: 3.3: Add note for legacy mcumgr rc responses
Adds a note on rc responses to mcumgr commands where the status is
good that these responses will henceforth be emitted.
@@ -429,6 +429,12 @@ Libraries / Subsystems
* MCUMgr :kconfig:option:`CONFIG_APP_LINK_WITH_MCUMGR` has been removed as
it has not been doing anything.
+ * MCUmgr responses where ``rc`` (result code) is 0 (no error) will no longer
+ be present in responses and in cases where there is only an ``rc`` result,
+ the resultant response will now be an empty CBOR map. The old behaviour can
+ be restored by enabling
+ :kconfig:option:`CONFIG_MCUMGR_SMP_LEGACY_RC_BEHAVIOUR`.
+
* LwM2M
* The ``lwm2m_senml_cbor_*`` files have been regenerated using zcbor 0.6.0.
