Replace CV.pdf with Resume.pdf and update reference

Removed the old CV.pdf, added Resume.pdf, and updated the cv.md page to reference the new PDF file.

Author: Keyu-He

_pages/cv.md

@@ -4,7 +4,7 @@ permalink: /cv/
 title: CV
 nav: true
 nav_order: 5
-cv_pdf: CV.pdf
+cv_pdf: Resume.pdf
 description: This is my CV. You can also download it as a PDF.
 toc:
   sidebar: left