Format Markdown using Prettier

docs/markdown-advanced.md

@@ -138,6 +138,7 @@ The rendered output looks like this:
 Here's a simple footnote,[^1] and here's a longer one.[^bignote]
 
 [^1]: This is the first footnote.
+
 [^bignote]: Here's one with multiple paragraphs and code.
 
     Indent paragraphs to include them in the footnote.