add migration note for users about tabId

MIGRATION.md

@@ -1,6 +1,7 @@
 <h1>Migration</h1>
 
 - [From version 7.x to 8.0.0](#from-version-7x-to-800)
+  - [Tab addons are now routed to a query parameter](#tab-addons-are-now-routed-to-a-query-parameter)
   - [Default keyboard shortcuts changed](#default-keyboard-shortcuts-changed)
   - [Manager addons are now rendered with React 18](#manager-addons-are-now-rendered-with-react-18)
   - [Removal of `storiesOf`-API](#removal-of-storiesof-api)
@@ -70,7 +71,7 @@
     - [`createChannel` from `@storybook/postmessage` and `@storybook/channel-websocket`](#createchannel-from-storybookpostmessage-and-storybookchannel-websocket)
     - [StoryStore and methods deprecated](#storystore-and-methods-deprecated)
   - [Addon author changes](#addon-author-changes)
-    - [Tab addons are now routed to a query parameter](#tab-addons-are-now-routed-to-a-query-parameter)
+    - [Tab addons cannot manually route, Tool addons can filter their visibility via tabId](#tab-addons-cannot-manually-route-tool-addons-can-filter-their-visibility-via-tabid)
     - [Removed `config` preset](#removed-config-preset-1)
 - [From version 7.5.0 to 7.6.0](#from-version-750-to-760)
     - [CommonJS with Vite is deprecated](#commonjs-with-vite-is-deprecated)
@@ -387,6 +388,12 @@
 
 ## From version 7.x to 8.0.0
 
+### Tab addons are now routed to a query parameter
+
+The URL of a tab used to be: `http://localhost:6006/?path=/my-addon-tab/my-story`.
+
+The new URL of a tab is `http://localhost:6006/?path=/story/my-story&tab=my-addon-tab`.
+
 ### Default keyboard shortcuts changed
 
 The default keyboard shortcuts have changed to avoid any conflicts with the browser's default shortcuts or when you are directly typing in the Manager. If you want to get the new default shortcuts, you can reset your shortcuts in the keyboard shortcuts panel by pressing the `Restore default` button.
@@ -1051,7 +1058,7 @@ Note that both these methods require initialization, so you should await `previe
 
 ### Addon author changes
 
-#### Tab addons are now routed to a query parameter
+#### Tab addons cannot manually route, Tool addons can filter their visibility via tabId
 
 The TAB type addons now should no longer specify the `match` or `route` property.
 
@@ -1091,8 +1098,6 @@ addons.register("my-addon", () => {
 });
 ```
 
-The URL the tab gets rendered on will be `http://localhost:6006/?path=/story/my-story&tab=my-addon/tab`.
-
 #### Removed `config` preset
 
 In Storybook 7.0 we have deprecated the preset field `config` and it has been replaced with `previewAnnotations`. The `config` preset is now completely removed in Storybook 8.0.