Merge pull request #762 from lightninglabs/docs-lnd

Update lnd documentation

Author: github-actions[bot]

docs/lnd/release-notes/release-notes-0.19.0.md

@@ -124,6 +124,18 @@
 
 * LND updates channel.backup file at shutdown time.
 
+* A new subsystem `chainio` is
+  [introduced](https://github.com/lightningnetwork/lnd/pull/9315) to make sure
+  the subsystems are in sync with their current best block. Previously, when
+  resolving a force close channel, the sweeping of HTLCs may be delayed for one
+  or two blocks due to block heights not in sync in the relevant subsystems
+  (`ChainArbitrator`, `UtxoSweeper` and `TxPublisher`), causing a slight
+  inaccuracy when deciding the sweeping feerate and urgency. With `chainio`,
+  this is now fixed as these subsystems now share the same view on the best
+  block. Check
+  [here](https://github.com/lightningnetwork/lnd/blob/master/chainio/README.md)
+  to learn more.
+
 ## RPC Updates
 
 * Some RPCs that previously just returned an empty response message now at least
@@ -209,6 +221,10 @@ The underlying functionality between those two options remain the same.
   estimator provided by bitcoind or btcd in regtest and simnet modes instead of
   static fee estimator if feeurl is not provided.
 
+* The integration tests CI have been optimized to run faster and all flakes are
+  now documented and
+  [fixed](https://github.com/lightningnetwork/lnd/pull/9368).
+
 ## Database
 
 * [Migrate the mission control