Use default mathjax location because setting it to anything else seems to break rmarkdown.

Fixes r-universe-org/help#619

Author: jeroen

R/articles.R

@@ -37,7 +37,6 @@ r_universe_format <- function(){
     toc = TRUE,
     toc_depth = 2,
     theme = NULL,
-    mathjax = NULL,
     highlight = 'pygments',
     template = template_file('template.html'),
     includes = rmarkdown::includes(

inst/rmd-template/template.html

@@ -36,6 +36,6 @@
 
       <!-- Mathjax -->
       <!-- <script src="https://polyfill.io/v3/polyfill.min.js?features=es6" data-external="1"></script> -->
-      <script id="MathJax-script" async src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/3.1.2/es5/tex-mml-chtml.min.js" data-external="1"></script>
+      <script id="MathJax-script" async src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/4.0.0/tex-mml-chtml.min.js" data-external="1"></script>
    </body>
 </html>