update migration guide

packages/toolkit/UPGRADING.md

@@ -7,6 +7,22 @@ There are a few major changes in this release. While it probably won't break you
 ### Node version
 Minimum Node version is now 18
 
+### useBlockAssets on by default.
+
+useBlockAssets is now true by default. If you are not ready for it yet. Set useBlockAssets to false in your 10up-toolkit package.json config.
+
+```json
+{
+  "name": "your-project",
+  "10up-toolkit": {
+    "useBlockAssets": false
+  }
+}
+```
+
+### Stylelint
+Stylelint has been updated to 15. When upgrading toolkit ensure you also update `@10up/stylelint-config` to 3, in case you are specifying it in your package.json. If you're not npm should resolve the peer dependency automatically.
+
 ### PostCSS
 Swapping `postcss-editor-styles` with `postcss-editor-styles-wrapper` which is compatible with PostCSS 8. This should be a seamless change as this is a fork of the original package that was updated to be compatible with PostCSS 8 and fixes wrong behaviour in some circumstances.
 
@@ -25,6 +41,8 @@ For those referencing `postcss-editor-styles` in `postcss.config.js` should upda
 ### Eslint
 The rule `jsdoc/newline-after-description` has been removed in the latest `eslint-plugin-jsdoc` and thus has been removed in the latest version of toolkit. If you have this rule in your own eslint config file you will need to remove it.
 
+When upgrading toolkit, ensure you also update `@10up/eslint-config` to 4, in case you are specifying it in your package.json. If you're not npm should resolve the peer depdency automatically.
+
 ### Prettier
 
 Prettier have been upgraded to v3. We also recommend that you specify a [prettier exact version](https://prettier.io/docs/en/install#summary) in your own package.json going forward. If you haven't, add prettier v3 to your package.json and if you already have prettier listed as a dependecy, update it to v3. Updating prettier will now be responsibility of the project since updating prettier often requires other code changes to adhere to new formatting rules.