Update auto-generated contract docs destination (#731)

As auto-generated contract API reference has been moved under
https://docs.threshold.network/app-development/tbtc-v2/tbtc-contracts-api,
we need to update the CI job that publishes those docs to take the new
destination into account

.github/workflows/contracts-docs.yml

@@ -78,7 +78,7 @@ jobs:
       addTOC: false
       verifyCommits: true
       destinationRepo: threshold-network/threshold
-      destinationFolder: ./docs/app-development/tbtc-v2/tbtc-v2-api
+      destinationFolder: ./docs/app-development/tbtc-v2/tbtc-contracts-api/tbtc-v2-api
       destinationBaseBranch: main
       userEmail: [email protected]
       userName: Valkyrie