Fix missing word in grid-auto-columns.mdx (#970)

Author: rleppink

src/pages/docs/grid-auto-columns.mdx

@@ -11,7 +11,7 @@ export const classes = { plugin }
 
 ## Usage
 
-Use the `auto-cols-{size}` utilities to control the size implicitly-created grid columns.
+Use the `auto-cols-{size}` utilities to control the size of implicitly-created grid columns.
 
 ```html
 <div class="grid grid-flow-col **auto-cols-max**">