docs: add release notes for v0.22.0

Add release notes entry for the AddHoldInvoice optional preimage/hash
generation feature under RPC Updates and lncli Updates.

Author: saubyk

docs/release-notes/release-notes-0.22.0.md

@@ -0,0 +1,75 @@
+# Release Notes
+- [Bug Fixes](#bug-fixes)
+- [New Features](#new-features)
+    - [Functional Enhancements](#functional-enhancements)
+    - [RPC Additions](#rpc-additions)
+    - [lncli Additions](#lncli-additions)
+- [Improvements](#improvements)
+    - [Functional Updates](#functional-updates)
+    - [RPC Updates](#rpc-updates)
+    - [lncli Updates](#lncli-updates)
+    - [Breaking Changes](#breaking-changes)
+    - [Performance Improvements](#performance-improvements)
+    - [Deprecations](#deprecations)
+- [Technical and Architectural Updates](#technical-and-architectural-updates)
+    - [BOLT Spec Updates](#bolt-spec-updates)
+    - [Testing](#testing)
+    - [Database](#database)
+    - [Code Health](#code-health)
+    - [Tooling and Documentation](#tooling-and-documentation)
+
+# Bug Fixes
+
+# New Features
+
+## Functional Enhancements
+
+## RPC Additions
+
+## lncli Additions
+
+# Improvements
+
+## Functional Updates
+
+## RPC Updates
+
+* [`AddHoldInvoice` now supports optional preimage/hash
+  generation](https://github.com/lightningnetwork/lnd/pull/10685). The `hash`
+  field is no longer required — when omitted, the server auto-generates a
+  cryptographically random preimage and derives the payment hash. A new
+  `preimage` field on the request allows callers to supply their own preimage
+  and let the server derive the hash, eliminating the risk of hash/preimage
+  mismatches. The response now includes `payment_preimage` (when the server
+  knows the preimage) and `payment_hash` (always populated).
+
+## lncli Updates
+
+* The [`addholdinvoice` command now accepts `--hash` and `--preimage`
+  flags](https://github.com/lightningnetwork/lnd/pull/10685). When neither is
+  provided, the server generates both automatically. The legacy positional hash
+  argument is still supported for backward compatibility.
+
+## Code Health
+
+## Breaking Changes
+
+## Performance Improvements
+
+## Deprecations
+
+# Technical and Architectural Updates
+
+## BOLT Spec Updates
+
+## Testing
+
+## Database
+
+## Code Health
+
+## Tooling and Documentation
+
+# Contributors (Alphabetical Order)
+
+* Suheb