Enable RFS for font resizing

- Enable RFS
- Add documentation
- Disable doc font size overrides

site/content/docs/4.3/getting-started/theming.md

@@ -270,7 +270,7 @@ You can find and customize these variables for key global options in Bootstrap's
 | `$enable-grid-classes`                       | `true` (default) or `false`        | Enables the generation of CSS classes for the grid system (e.g., `.container`, `.row`, `.col-md-1`, etc.). |
 | `$enable-caret`                              | `true` (default) or `false`        | Enables pseudo element caret on `.dropdown-toggle`. |
 | `$enable-pointer-cursor-for-buttons`         | `true` (default) or `false`        | Add "hand" cursor to non-disabled button elements. |
-| `$enable-responsive-font-sizes`              | `true` or `false` (default)        | Enables [responsive font sizes]({{< docsref "/content/typography#responsive-font-sizes" >}}). |
+| `$enable-rfs`                                | `true` or `false` (default)        | Globally enables [RFS]({{< docsref "/getting-started/rfs" >}}). |
 | `$enable-validation-icons`                   | `true` (default) or `false`        | Enables `background-image` icons within textual inputs and some custom forms for validation states. |
 | `$enable-deprecation-messages`               | `true` or `false` (default)        | Set to `true` to show warnings when using any of the deprecated mixins and functions that are planned to be removed in `v5`. |