Potential fix for code scanning alert no. 2: Useless regular-expression character escape

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

Author: nigelhorne

js/Markdown.Converter.js

@@ -1165,7 +1165,7 @@ else
             text = text.replace(/>/g, ">");
 
             // Now, escape characters that are magic in Markdown:
-            text = escapeCharacters(text, "\*_{}[]\\", false);
+            text = escapeCharacters(text, "\\*_{}[]\\\\", false);
 
             // jj the line above breaks this:
             //---