Update buttons.md (#38169)

* Update buttons.md

Updates the buttons documentation to refer to the button styles as variants as opposed to "predefined styles" as that language was previously troublesome elsewhere in our docs, and variants makes more sense.

* Update site/content/docs/5.3/components/buttons.md

Co-authored-by: Julien Déramond <julien.deramond@orange.com>

---------

Co-authored-by: Julien Déramond <julien.deramond@orange.com>

site/content/docs/5.3/components/buttons.md

@@ -14,15 +14,15 @@ Bootstrap has a base `.btn` class that sets up basic styles such as padding and
 <button type="button" class="btn">Base class</button>
 {{< /example >}}
 
-The `.btn` class is intended to be used in conjunction with our additional predefined button styles, or to serve as a basis for your own custom styles.
+The `.btn` class is intended to be used in conjunction with our button variants, or to serve as a basis for your own custom styles.
 
 {{< callout warning >}}
 If you are using the `.btn` class on its own, remember to at least define some explicit `:focus` and/or `:focus-visible` styles.
 {{< /callout >}}
 
-## Predefined styles
+## Variants
 
-Bootstrap includes several predefined button styles, each serving its own semantic purpose, with a few extras thrown in for more control.
+Bootstrap includes several button variants, each serving its own semantic purpose, with a few extras thrown in for more control.
 
 {{< example >}}
 {{< buttons.inline >}}