doc: Update issue reference for libbitcoinkernel

The discussion of libbitcoinkernel has moved from #24303 to #27587,
this commit updates the documentation accordingly.

Author: danielabrozzoni

doc/design/libraries.md

@@ -109,5 +109,5 @@ class bitcoin-qt,bitcoind,bitcoin-cli,bitcoin-wallet bold
 
 ## Work in progress
 
-- Validation code is moving from *libbitcoin_node* to *libbitcoin_kernel* as part of [The libbitcoinkernel Project #24303](https://github.com/bitcoin/bitcoin/issues/24303)
+- Validation code is moving from *libbitcoin_node* to *libbitcoin_kernel* as part of [The libbitcoinkernel Project #27587](https://github.com/bitcoin/bitcoin/issues/27587)
 - Source code organization is discussed in general in [Library source code organization #15732](https://github.com/bitcoin/bitcoin/issues/15732)