Update documentation to point to the right example (#2993)

Author: campeis

website/versioned_docs/version-0.20/migration-guides/yew-agent/from-0_1_0-to-0_2_0.mdx

@@ -6,7 +6,7 @@ title: 'From 0.1.0 to 0.2.0'
 
 The `Context` and `Job` Agents have been removed in favour of Yew's Context API.
 
-You can see the updated [`pub_sub`](https://github.com/yewstack/yew/tree/master/examples/pub_sub)
+You can see the updated [`contexts`](https://github.com/yewstack/yew/tree/master/examples/contexts)
 which demonstrate how to use the context API.
 
 For users of `yew_agent::utils::store`, you may switch to third party solutions like: [Yewdux](https://github.com/intendednull/yewdux) or [Bounce](https://github.com/futursolo/bounce).