Stage 3 instruction ambiguous - "Update specs/" unclear about source/destination

[KoalaHao]

Current:

• Update specs/ if capabilities changed

Problem:
AI models are sometimes confused about:

1. Which specs/ directory to update (source vs destination)
2. Where to read delta changes from
3. Whether "update" means merge, overwrite, or apply

This leads to models writing to changes/[name]/specs/ instead of openspec/specs/, or not understanding the delta merge workflow.

Suggested fix:

• Merge delta specs from changes/[name]/specs/ into openspec/specs/ if capabilities changed

Why this helps:

• Explicitly names both source (changes/[name]/specs/) and destination (openspec/specs/)
• Uses "merge" to clarify the operation combines deltas with existing specs