FailedChanges

Summary

  1. [SPARK-25754][DOC] Change CDN for MathJax (details)
Commit 2ab4473bed44828cee5a47759b5c36fc81dd5d71 by sean.owen
[SPARK-25754][DOC] Change CDN for MathJax
## What changes were proposed in this pull request?
Currently when we open our doc site:
https://spark.apache.org/docs/latest/index.html , there is one warning
![image](https://user-images.githubusercontent.com/1097932/47065926-2b757980-d217-11e8-868f-02ce73f513ae.png)
This PR is to change the CDN as per the migration tips:
https://www.mathjax.org/cdn-shutting-down/
This is very very trivial. But it would be good to follow the suggestion
from MathJax team and remove the warning, in case one day the original
CDN is no longer available.
## How was this patch tested?
Manual check.
Closes #22753 from gengliangwang/migrateMathJax.
Authored-by: Gengliang Wang <gengliang.wang@databricks.com>
Signed-off-by: Sean Owen <sean.owen@databricks.com>
The file was modifieddocs/_layouts/global.html (diff)
The file was modifieddocs/js/api-docs.js (diff)