docs: remove deleted project docs skill requirement

.project-docs/05-agent-entry/memory-index.md

@@ -1,6 +1,6 @@
 # Memory Index
 
-Use this as the high-density entry point after the Concurrent Task Gate establishes task identity and worktree ownership.
+Use this as the high-density entry point after the repository-local Concurrent Worktree Check establishes the current branch, worktree, status, and task scope.
 
 ## Startup Set