docs: add guidance for project documentation capture (#355)

examples/user-CLAUDE.md

@@ -79,6 +79,12 @@ Located in `~/.claude/agents/`:
 - 80% minimum coverage
 - Unit + integration + E2E for critical flows
 
+### Knowledge Capture
+- Personal debugging notes, preferences, and temporary context → auto memory
+- Team/project knowledge (architecture decisions, API changes, implementation runbooks) → follow the project's existing docs structure
+- If the current task already produces the relevant docs, comments, or examples, do not duplicate the same knowledge elsewhere
+- If there is no obvious project doc location, ask before creating a new top-level doc
+
 ---
 
 ## Editor Integration