fix: use jsdelivr.net

Author: HowCam

mkdocs.yml

@@ -171,9 +171,9 @@ markdown_extensions:
 
 
 extra_javascript:
-  - https://jsd.cdn.zzko.cn/npm/js-polyfills@0.1.43/polyfill.min.js
-  - https://jsd.cdn.zzko.cn/npm/mathjax@3/es5/tex-chtml.js
+  - https://cdn.jsdelivr.net/npm/js-polyfills@0.1.43/polyfill.min.js
+  - https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js
 
 extra_css:
   - style/extra.css
-  - https://jsd.cdn.zzko.cn/npm/lxgw-wenkai-screen-webfont@1.1.0/style.css
+  - https://cdn.jsdelivr.net/npm/lxgw-wenkai-screen-webfont@1.1.0/style.css