fix(memory): correct quiz Q2 answer from discontinued # prefix to /memory (#107)

The lesson quiz Q2 had `#` prefix as the correct answer for adding
memory rules, but the lesson README explicitly states this was
discontinued. Update answer to `/memory` or conversational request,
and fix a residual `#` prefix reference in the README's "Quick
update workflow" section.

Closes #106

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

02-memory/README.md

@@ -992,7 +992,7 @@ graph LR
 
 **Quick update workflow:**
 
-1. For single rules: Use `#` prefix in conversation
+1. For single rules: Use `/memory` to open editor, or ask conversationally
 2. For multiple changes: Use `/memory` to open editor
 3. For initial setup: Use `/init` to create template