Merge bitcoin#19802: doc: elaborate on release notes wrt netmasks

8de51d1 doc: elaborate on release notes wrt netmasks (Vasil Dimov)

Pull request description:

  doc: elaborate on release notes wrt netmasks

  A minor followup from bitcoin#19628 (comment).

ACKs for top commit:
  laanwj:
    ACK bitcoin@8de51d1
  practicalswift:
    ACK 8de51d1
  theStack:
    ACK 8de51d1

Tree-SHA512: ccece7c3057e476d59e9996582e8594b3db9eaed397139217335a41307e542194c8d13ad72458eaa8580a5c469fef9cc9e3f11c1c609617757579530b465e5b0

Author: laanwj

doc/release-notes.md

@@ -155,7 +155,8 @@ Updated settings
 
 - Netmasks that contain 1-bits after 0-bits (the 1-bits are not contiguous on
   the left side, e.g. 255.0.255.255) are no longer accepted. They are invalid
-  according to RFC 4632.
+  according to RFC 4632. Netmasks are used in the `-rpcallowip` and `-whitelist`
+  configuration options and in the `setban` RPC. (#19628)
 
 Changes to Wallet or GUI related settings can be found in the GUI or Wallet  section below.