docs: clarify plugins don't update devtools timeline (#1002)

Co-authored-by: Eduardo San Martin Morote <[email protected]>

Author: Matt-Deacalion

packages/docs/core-concepts/plugins.md

@@ -131,6 +131,8 @@ pinia.use(({ store }) => {
 })
 ```
 
+Note that state changes or additions that occur within a plugin (that includes calling `store.$patch()`) happen before the store is active and therefore **do not trigger any subscriptions**.
+
 :::warning
 If you are using **Vue 2**, Pinia is subject to the [same reactivity caveats](https://vuejs.org/v2/guide/reactivity.html#Change-Detection-Caveats) as Vue. You will need to use `set` from `@vue/composition-api` when creating new state properties like `secret` and `hasError`: