update mathjax v2 example

Author: archmoj

README.md

@@ -140,27 +140,10 @@ These pages are generated by the Plotly [graphing-library-docs repo](https://git
 For more info about contributing to Plotly documentation, please read through [contributing guidelines](https://github.com/plotly/graphing-library-docs/blob/master/README.md).
 
 ### To support MathJax
-
-*Before* the plotly.js script tag, add:
-
-```html
-<script src="mathjax/MathJax.js?config=TeX-AMS-MML_SVG"></script>
-```
-
-You can get the relevant MathJax files from the internet e.g.
-"https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/MathJax.js?config=TeX-AMS-MML_SVG.js"
-
-By default, plotly.js will modify the global MathJax configuration on load.
-This can lead to undesirable behavior if plotly.js is loaded alongside
-other libraries that also rely on MathJax. To disable this global configuration
-process, set the `MathJaxConfig` property to `'local'` in the `window.PlotlyConfig`
-object.  This property must be set before the plotly.js script tag, for example:
-
+Load relevant MathJax (v2) files *Before* the plotly.js script tag:
 ```html
-<script>
-   window.PlotlyConfig = {MathJaxConfig: 'local'}
-</script>
-<script src="plotly.min.js"></script>
+<script src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/MathJax.js?config=TeX-AMS-MML_SVG.js"></script>
+<script src="https://cdn.plot.ly/plotly-2.0.0-rc.2.min.js"></script>
 ```
 
 ---