guix: move bitcoin.conf to /share/examples dir

Motivated by bitcoin#29139

Placing the example `bitcoin.conf` file in this directory makes it
clearer that it will not actively be used by the binary in `bin/`, and
must be moved elsewhere.

contrib/guix/libexec/build.sh

@@ -356,7 +356,8 @@ mkdir -p "$DISTSRC"
 
         # copy over the example bitcoin.conf file. if contrib/devtools/gen-bitcoin-conf.sh
         # has not been run before buildling, this file will be a stub
-        cp "${DISTSRC}/share/examples/bitcoin.conf" "${DISTNAME}/"
+        mkdir -p "${DISTNAME}/share/examples"
+        cp "${DISTSRC}/share/examples/bitcoin.conf" "${DISTNAME}/share/examples/"
 
         cp -r "${DISTSRC}/share/rpcauth" "${DISTNAME}/share/"