fix: indent YAML properties under with: in nested example

The nested markdown example had with: properties not indented, which would
produce invalid YAML when copy-pasted into a README. Properly indent
anthropic_api_key, prompt, and claude_args under with:.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: sjnims

plugins/plugin-dev/skills/plugin-structure/references/github-actions.md

@@ -208,13 +208,12 @@ Include example workflow snippets in your plugin README:
 Add to `.github/workflows/claude.yml`:
 
 \`\`\`yaml
-
 - uses: anthropics/claude-code-action@v1
   with:
-  anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
-  prompt: "Analyze code using [your-plugin] standards"
-  claude_args: "--max-turns 15 --allowedTools 'Read,Grep,Glob'"
-  \`\`\`
+    anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
+    prompt: "Analyze code using [your-plugin] standards"
+    claude_args: "--max-turns 15 --allowedTools 'Read,Grep,Glob'"
+\`\`\`
 ```
 
 ### Ensure CI Compatibility