docs: add ''Mithril client WASM breaking-change' dev blog post

docs/website/blog/2024-09-24-client-wasm-unstable-breaking-change.md

@@ -0,0 +1,44 @@
+---
+title: Mithril client WASM breaking change
+authors:
+  - name: Mithril Team
+tags: [mithril client, cli, breaking-change]
+---
+
+### Breaking change introduced in the unstable features of the Mithril client WASM
+
+With the release of the new distribution [2437](https://github.com/input-output-hk/mithril/releases/tag/2437.1), we have introduced a breaking change to the **Mithril client WASM** version `0.4.1`: the activation of the unstable features is now done with a **configuration option of the client** instead of using the special `.unstable` property of the client.
+
+This means that when a new `unstable` feature is switched to `stable`, there will be no breaking change in the developers code using the Mithril client WASM, thus providing a seamless transition and a better developer experience.
+
+Here is the code used to activate the `unstable` features with the client options:
+
+```js
+let client = new MithrilClient(aggregator_endpoint, genesis_verification_key, {
+  // The following option activates the unstable features of the client.
+  // Unstable features will trigger an error if this option is not set.
+  unstable: true,
+});
+```
+
+The previous `client.unstable` implementation is not supported anymore and must be replaced with `client`:
+
+```js
+// Before
+let mithril_stake_distributions_message =
+  await client.unstable.compute_mithril_stake_distribution_message(
+    last_stake_distribution,
+  );
+```
+
+```js
+// After
+let mithril_stake_distributions_message =
+  await client.compute_mithril_stake_distribution_message(
+    last_stake_distribution,
+  );
+```
+
+The Mithril client WASM documentation is available [here](https://mithril.network/doc/manual/developer-docs/nodes/mithril-client-library-wasm).
+
+For any inquiries or assistance, don't hesitate to reach out to the team on the [Discord channel](https://discord.gg/5kaErDKDRq).