add news item

Author: salim-b

Diff for: NEWS.md

@@ -8,6 +8,8 @@
 
 * All HTTP requests are now retried upon failure (#1656)
 
+* R linebreaks (`\n`) in _factor labels_ are now translated to HTML linebreaks (`<br />`), too. Before, this conversion was only done for colums of type character. ([#1700](https://github.com/ropensci/plotly/pull/1700), @salim-b)
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 ## BUG FIXES
 
 * `ggplotly()` now handles discrete axes of a `facet_wrap` and `facet_grid` correctly when there is only one category in panels > 1 (#1577 and #1720).