[3.x] Update check prop & upgrade guide

src/3.x/graphql-components.md

@@ -30,7 +30,7 @@ Prop | Type | Default | Explanation
 `variables` | Object | `{}` | GraphQL variables
 `store` | String | `window.config.store_code` | Store code
 [`group`](#grouping) | String | | Bundle queries by a name into 1 request [see: group](#grouping)
-`check` | String | | Run a check on the response data, for example: `check="data.countries[0] == 'Country'"`
+`check` | Function | | Run a check on the response data, for example: `check="(data) => data.countries[0] == 'Country'"`
 `redirect` | String | | Where to redirect if the check fails
 `cache` | String | | Cache key in localstorage. Caches only when provided and will be prefixed with `graphql_`. Flushes when the [cache](cache.md) is cleared.
 `callback` | Function | | Called after the query

src/3.x/upgrading.md

@@ -39,7 +39,8 @@ class Authenticate extends Middleware
 }
 ```
 
-## Frontend dependencies
+## Frontend changes
+### Dependencies
 
 1. **Install**
 ```
@@ -54,6 +55,10 @@ yarn build
 
 If you need to interact with the current Vue instance, do not use `turbo:load`. Instead use `vue:loaded` to ensure Vue has actually been booted.
 
+### Graphql component
+
+The `check` property on the graphql component has been changed from a string that gets evaluated to a function. This means that you will have to update each (normal) usage of `check="[...]"` to `check="(data) => data.[...]"`.
+
 ## Checkout changes
 
 Everything has been migrated to use the GraphQL components for queries and mutations. On those components callbacks are used to process the data. So any changes made in an overwritten `checkout.vue` file and any checkout views should be reviewed.