[doc] update release notes for 28.x

doc/release-notes.md

@@ -37,6 +37,22 @@ unsupported systems.
 Notable changes
 ===============
 
+### Policy
+
+ The minimum block feerate (`-blockmintxfee`) has been changed to 1 satoshi per kvB. It can still be changed using the
+configuration option.
+
+- The default minimum relay feerate (`-minrelaytxfee`) and incremental relay feerate (`-incrementalrelayfee`) have been
+changed to 100 satoshis per kvB. They can still be changed using their respective configuration options, but it is
+recommended to change both together if you decide to do so.
+  - Other minimum feerates (e.g. the dust feerate, the minimum returned by the fee estimator, and all feerates used by
+  the wallet) remain unchanged. The mempool minimum feerate still changes in response to high volume.
+  - Note that unless these lower defaults are widely adopted across the network, transactions created with lower fee
+  rates are not guaranteed to propagate or confirm. The wallet feerates remain unchanged; `-mintxfee` must be changed
+  before attempting to create transactions with lower feerates using the wallet.
+
+- #33106 policy: lower the default blockmintxfee, incrementalrelayfee, minrelaytxfee
+
 ### P2P
 
 - #33395 net: do not apply whitelist permissions to onion inbounds
@@ -45,6 +61,9 @@ Notable changes
 
 - #32765 test: Fix list index out of range error in feature_bip68_sequence.py
 - #33001 test: Do not pass tests on unhandled exceptions
+- #30125 test: improve BDB parser (handle internal/overflow pages, support all page sizes)
+- #30948 test: Add missing sync_mempools() to fill_mempool()
+- #30784 test: add BulkTransaction helper to unit test transaction utils
 
 ### Build
 
@@ -70,6 +89,7 @@ Credits
 Thanks to everyone who directly contributed to this release:
 - 0xB10C
 - fanquake
+- glozow
 - Hennadii Stepanov
 - MarcoFalke
 - Martin Zumsande