update: use zhihu unpkg mirror (#45)

* update: add latex support

* update: use zhihu unpkg mirror

mkdocs.yml

@@ -131,7 +131,7 @@ theme:
 extra_javascript:
     - 'javascripts/analysis.js'
     - 'javascripts/mathjax.js'
-    - 'https://unpkg.com/mathjax@3/es5/tex-mml-chtml.js'
+    - 'https://unpkg.zhimg.com/mathjax@3/es5/tex-mml-chtml.js'
 
 repo_url: https://github.com/west2-online/fzu-run
 repo_name: west2-online/fzu-run