update news

Author: cpsievert

NEWS.md

@@ -15,6 +15,7 @@
 
 ### Other improvements relevant for all **plotly** objects
 
+* TeX rendering via MathJax is now supported (#375). Use the new `mathjax` argument in `config()` to specify either external (`mathjax="cdn"`) or local (`mathjax="local"`) MathJaX. If `"cdn"`, mathjax is loaded externally (meaning an internet connection is needed for TeX rendering). If `"local"`, the PLOTLY_MATHJAX_PATH environment variable must be set to the location (a local file path) of MathJax. IMPORTANT: **plotly** uses SVG-based mathjax rendering which doesn't play nicely with HTML-based rendering (e.g., rmarkdown documents). In this case, consider `<iframe>`-ing your plotly graph(s) into the larger document (see [here](https://github.com/ropensci/plotly/blob/master/inst/examples/rmd/MathJax/index.Rmd) for an example).
 * The selection (i.e., linked-brushing) mode can now switch from 'transient' to 'persistent' by holding the 'shift' key. It's still possible to _force_ persistent selection by setting `persistent = TRUE` in `highlight()`, but `persistent = FALSE` (the default) is now recommended since it allows one to switch between [persistent/transient selection](https://plotly-book.cpsievert.me/linking-views-without-shiny.html#transient-versus-persistent-selection) in the browser, rather than at the command line.
 * The `highlight()` function gains a `debounce` argument for throttling the rate at which `on` events may be fired. This is mainly useful for improving user experience when `highlight(on = "plotly_hover")` and mousing over relevant markers at a rapid rate (#1277)
 * The new `partial_bundle()` function makes it easy to leverage [partial bundles of plotly.js](https://github.com/plotly/plotly.js#partial-bundles) for reduced file sizes and faster render times.