Improve release note for 0.29.1

Summary: As per title.

Test Plan: Read it.

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D15900

Author: Fabcien

doc/release-notes.md

@@ -5,4 +5,4 @@ Bitcoin ABC version 0.29.1 is now available from:
   <https://download.bitcoinabc.org/0.29.1/>
 
 This is a hotfix release to fix a bug that could cause the node to connect
-to the same peer twice.
+to the same peer twice. Only v0.29.0 is affected by the bug.