Use real classes instead of bg-*

Author: reinink

src/pages/docs/background-color.mdx

@@ -36,7 +36,7 @@ export const classes = {
 
 ### Setting the background color
 
-Use the `bg-*` utilities to control the background color of an element.
+Use utilities like `bg-white`, `bg-indigo-500` and `bg-transparent` to control the background color of an element.
 
 ```html {{ example: true }}
 <div class="text-center">

src/pages/docs/background-position.mdx

@@ -14,7 +14,7 @@ export const classes = { utilities }
 
 ### Setting the background position
 
-Use the `bg-*` utilities to control the position of an element's background image.
+Use utilities like `bg-center`, `bg-right`, and `bg-left-top` to the position of an element's background image.
 
 ```html {{ example: { p: 'none' } }}
 <div class="w-full">