Add callout component (#759)

<!-- Explain the changes introduced in your PR -->

I missed the link, adding a callout will make sure others don't do the
same

## Pull Request approval

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Sourcegraph team. For reviews of docs formatting, styles, and component
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Author: jdorfman

docs/admin/pricing.mdx

@@ -1,6 +1,6 @@
 # Pricing
 
-Visit the [pricing page](https://about.sourcegraph.com/pricing) for up-to-date pricing. 
+<Callout type="note">Visit the [pricing page](https://about.sourcegraph.com/pricing) for up-to-date pricing.</Callout>
 
 ## How are active users calculated for **Sourcegraph Cody**?