Merge bitcoin/bitcoin#22603: doc: Add release notes for 22570 (ignore banlist.dat)

fa2c868 doc: Add release notes for 22570 (ignore banlist.dat) (MarcoFalke)

Pull request description:

  Follow-up to #22570

ACKs for top commit:
  tryphe:
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  vasild:
    ACK fa2c868
  Zero-1729:
    ACK fa2c868

Tree-SHA512: 58eef340b6211bcdecf3826ac145afd476c397f110daa6783521c0c1e1be1ffbd2d24ad20c77921abbe5cdb8e644d3cd64e14e2819746cf0e5123fb7cc445d63

Author: MarcoFalke

doc/release-notes.md

@@ -66,6 +66,16 @@ New RPCs
 Build System
 ------------
 
+Files
+-----
+
+* On startup, the list of banned hosts and networks (via `setban` RPC) in
+  `banlist.dat` is ignored and only `banlist.json` is considered. Bitcoin Core
+  version 22.x is the only version that can read `banlist.dat` and also write
+  it to `banlist.json`. If `banlist.json` already exists, version 22.x will not
+  try to translate the `banlist.dat` into json. After an upgrade, `listbanned`
+  can be used to double check the parsed entries. (#22570)
+
 New settings
 ------------