fix(lint): allow code element in markdownlint MD033 rule

The README troubleshooting section uses <code> inside <summary> tags
for collapsible sections. Add code to the MD033 allowed_elements list.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: rjmurillo-bot

.markdownlint-cli2.yaml

@@ -55,6 +55,7 @@ config:
       - details
       - summary
       - strong
+      - code
       - example
 
   # Multiple H1 - allow in agent templates (frontmatter can create implicit H1)