docs: update release notes

Author: ellemouton

docs/release-notes/release-notes-0.20.1.md

@@ -32,6 +32,11 @@
   addresses](https://github.com/lightningnetwork/lnd/pull/10341) were added to
   the node announcement and `getinfo` output.
 
+* Fix a bug where [missing edges for own channels could not be added to the
+  graph DB](https://github.com/lightningnetwork/lnd/pull/10410)
+  due to validation checks in the graph Builder that were resurfaced after the
+  graph refactor work.
+
 # New Features
 
 ## Functional Enhancements