fix: add alt in _index.html img tag

Author: RayCC51

content/_index.html

@@ -53,4 +53,5 @@ <h2>Hello, I am ...</h2>
 <img
   id="github-stat"
   src="https://github-readme-stats.vercel.app/api?username=raycc51&show_icons=true&theme=transparent&title_color=bf4040&icon_color=bf4040&text_color=8f8d8d&border_radius=5"
+  alt="github stat of raycc51"
 />