docs(forms-layout): fix simple typo (#6668)

www/docs/forms/layout.mdx

@@ -99,7 +99,7 @@ like `<Col xs={7}>`.
 
 The example below uses a flexbox utility to vertically center the contents and
 changes `<Col>` to `<Col xs="auto">` so that your columns only take up as much
-space as needed. Put another way, the column sizes itself based on on the contents.
+space as needed. Put another way, the column sizes itself based on the contents.
 
 <CodeBlock language="jsx" live>
   {GridAutoSizing}