document it

diff --git a/docs/4.0/components/buttons.md b/docs/4.0/components/buttons.md
index 41ca9cef075a87dca1d199eda98934e27742fbbb..6dfed7ddf2f57952a52b446b25c4fd7586781dd0 100644 (file)
--- a/docs/4.0/components/buttons.md
+++ b/docs/4.0/components/buttons.md
@@ -116,14 +116,14 @@ Add `data-toggle="button"` to toggle a button's `active` state. If you're pre-to
 
 ### Checkbox and radio buttons
 
-Bootstrap's `.button` styles can be applied to other elements, such as `<label>`s, to provide checkbox or radio style button toggling. Add `data-toggle="buttons"` to a `.btn-group` containing those modified buttons to enable toggling in their respective styles.
+Bootstrap's `.button` styles can be applied to other elements, such as `<label>`s, to provide checkbox or radio style button toggling. Add `data-toggle="buttons"` to a `.btn-group` containing those modified buttons to enable their toggling behavior via JavaScript and add `.btn-group-toggle` to style the `<input>`s within your buttons.
 
 The checked state for these buttons is **only updated via `click` event** on the button. If you use another method to update the input—e.g., with `<input type="reset">` or by manually applying the input's `checked` property—you'll need to toggle `.active` on the `<label>` manually.
 
 Note that pre-checked buttons require you to manually add the `.active` class to the input's `<label>`.
 
 {% example html %}
-<div class="btn-group" data-toggle="buttons">
+<div class="btn-group btn-group-toggle" data-toggle="buttons">
   <label class="btn btn-secondary active">
     <input type="checkbox" checked autocomplete="off"> Checkbox 1 (pre-checked)
   </label>