docs: add release-notes.

docs/release-notes/release-notes-0.18.0.md

@@ -36,6 +36,12 @@
   might panic due to empty witness data found in a transaction. More details
   can be found [here](https://github.com/bitcoin/bitcoin/issues/28730).
 
+* [Fixed](https://github.com/lightningnetwork/lnd/pull/7805) a case where `lnd`
+  might propose a low fee rate for the channel (when initiator) due to the
+  mempool not having enough data yet or the channel might be drained locally
+  which with the default fee allocation in place will eventually lead to the
+  downsizing to the fee floor (1 sat/vbyte) in the worst case.
+
 # New Features
 ## Functional Enhancements