Merge bitcoin/bitcoin#24345: doc: Release process: fix broken link to Guix building docs

64645fa Release process: fix broken link to Guix building docs (Jeremy Rand)

Pull request description:

  Not 100% sure whether this link was always broken or if the Guix docs renamed the heading at some point.  Either way, seems good to fix it.

ACKs for top commit:
  fanquake:
    ACK 64645fa

Tree-SHA512: 4932059fe583c0d27c70febf8f4dd8cffd3e15567359c5429d2691e221afc6da319bf43ebcd264ae0f98302e1eeb67ffd763d3d7d06ab1633913555ee7461643

Author: fanquake

doc/release-process.md

@@ -118,7 +118,7 @@ details.
 ### Build and attest to build outputs:
 
 Follow the relevant Guix README.md sections:
-- [Performing a build](/contrib/guix/README.md#performing-a-build)
+- [Building](/contrib/guix/README.md#building)
 - [Attesting to build outputs](/contrib/guix/README.md#attesting-to-build-outputs)
 
 ### Verify other builders' signatures to your own. (Optional)