docs: add release notes

Author: darioAnongba

docs/release-notes/release-notes-0.8.0.md

@@ -37,6 +37,11 @@
 
 ## Functional Updates
 
+- [Garbage collection of zero-value UTXOs](https://github.com/lightninglabs/taproot-assets/pull/1832)
+  by sweeping tombstones and burn outputs when executing onchain transactions.
+  Garbage collection will be executed on every burn, transfer or call to
+  `AnchorVirtualPsbts`.
+
 ## RPC Updates
 
 - [PR#1841](https://github.com/lightninglabs/taproot-assets/pull/1841): Remove