docs: fix EstimateRouteFee PR link

Update the release note link to the actual draft PR number.

Author: yyforyongyu

docs/release-notes/release-notes-0.21.0.md

@@ -88,7 +88,7 @@
   RBF close state machine does not yet thread through the `AuxCloser` hook
   that overlay channels rely on to build aux-aware close transactions.
 
-* [Fixed `EstimateRouteFee`](https://github.com/lightningnetwork/lnd/pull/10780)
+* [Fixed `EstimateRouteFee`](https://github.com/lightningnetwork/lnd/pull/10771)
   to use independent probe payment hashes when probing multiple LSPs, preventing
   later probes from reusing the first probe's CLTV delta.