docs: update migration guide (#927)

Author: MarcusNotheis

docs/2-MigrationGuide.stories.mdx

@@ -23,8 +23,41 @@ or the [changelog](https://github.com/SAP/ui5-webcomponents-react/blob/master/CH
 
 <br />
 
+### Updated import paths for `icons`
+
+All icons imports are changed. The individual icons modules are available in the icon package's `dist` folder.
+If you previously had `import "@ui5/webcomponents-icons/dist/icons/accept.js"`, now it becomes `import "@ui5/webcomponents-icons/dist/accept.js";`.
+
+<br />
+
+### API Updates
+
+The `Toolbar` was firing an event `onToolbarClick`. This event has been replaced with `onClick`.
+
+<br />
+
 ### Deleted Components
 
+<br />
+
+#### Spinner
+
+The deprecated `Spinner` component has been removed in favor of the [BusyIndicator](https://sap.github.io/ui5-webcomponents-react/?path=/docs/ui5-web-components-busyindicator) component.
+
+Migration Example:
+
+```jsx
+<Spinner size={Size.Large} delay={1000} />
+```
+
+will become
+
+```jsx
+<BusyIndicator size={BusyIndicatorSize.Large} active />
+```
+
+#### Tokenizer
+
 The deprecated `Tokenizer` component has been removed in favor of the [MultiInput](https://sap.github.io/ui5-webcomponents-react/?path=/docs/ui5-web-components-multiinput) component.
 
 Migration Example: