[doc] add release notes for 26.1rc1

doc/release-notes.md

@@ -1,9 +1,9 @@
-26.x Release Notes
+26.1rc1 Release Notes
 ==================
 
-Bitcoin Core version 26.x is now available from:
+Bitcoin Core version 26.1rc1 is now available from:
 
-  <https://bitcoincore.org/bin/bitcoin-core-26.x/>
+  <https://bitcoincore.org/bin/bitcoin-core-26.1/test.rc1/>
 
 This release includes new features, various bug fixes and performance
 improvements, as well as updated translations.
@@ -50,22 +50,45 @@ Notable changes
 
 - #29003 rpc: fix getrawtransaction segfault
 
+### Logs
+
+- #29227 log mempool loading progress
+
+### P2P and network changes
+
+- #29200 net: create I2P sessions using both ECIES-X25519 and ElGamal encryption
+
+### Build
+
+- #29127 Use hardened runtime on macOS release builds.
+- #29195 build: Fix -Xclang -internal-isystem option
+
 ### CI
 
 - #28992 ci: Use Ubuntu 24.04 Noble for asan,tsan,tidy,fuzz
 - #29080 ci: Set HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK to avoid unrelated failures
 
+### Miscellaneous
+
+- #28391 refactor: Simplify CTxMempool/BlockAssembler fields, remove some external mapTx access
+- #29179 test: wallet rescan with reorged parent + IsFromMe child in mempool
+- #28791 snapshots: don't core dump when running -checkblockindex after loadtxoutset
+
 Credits
 =======
 
 Thanks to everyone who directly contributed to this release:
 
-- Andrew Chow
+- fanquake
 - furszy
+- glozow
 - Hennadii Stepanov
+- Jon Atack
 - MarcoFalke
+- Mark Friedenbach
 - Martin Zumsande
 - Murch
+- stickies-v
 
 As well as to everyone that helped with translations on
 [Transifex](https://www.transifex.com/bitcoin/bitcoin/).