typography.md: update wording about RFS and Bootstrap version.

diff --git a/site/docs/4.5/content/typography.md b/site/docs/4.5/content/typography.md
index 2d53fe6401de9414bac992985d28f7cb4a6a1fb1..b568d20f22ce7dcc5a6f78a63c68a5cefafc20a1 100644 (file)
--- a/site/docs/4.5/content/typography.md
+++ b/site/docs/4.5/content/typography.md
@@ -296,6 +296,6 @@ Align terms and descriptions horizontally by using our grid system's predefined
 
 ## Responsive font sizes
 
-Bootstrap v4.3 ships with the option to enable responsive font sizes, allowing text to scale more naturally across device and viewport sizes. <abbr title="Responsive font sizes">RFS</abbr> can be enabled by changing the `$enable-responsive-font-sizes` Sass variable to `true` and recompiling Bootstrap.
+As of v4.3.0, Bootstrap ships with the option to enable responsive font sizes, allowing text to scale more naturally across device and viewport sizes. <abbr title="Responsive font sizes">RFS</abbr> can be enabled by changing the `$enable-responsive-font-sizes` Sass variable to `true` and recompiling Bootstrap.
 
 To support <abbr title="Responsive font sizes">RFS</abbr>, we use a Sass mixin to replace our normal `font-size` properties. Responsive font sizes will be compiled into `calc()` functions with a mix of `rem` and viewport units to enable the responsive scaling behavior. More about <abbr title="Responsive font sizes">RFS</abbr> and its configuration can be found on its [GitHub repository](https://github.com/twbs/rfs/tree/v8.0.4).