update(docs): Update checkbox.md (#8576)

Current documentation for checkbox is outdated. Also maybe you should add description for `graphql.isNonNull.update`

docs/pages/docs/fields/checkbox.md

@@ -9,11 +9,11 @@ Options:
 
 - `defaultValue` (default: `false`): This value will be used for the field when creating items if no explicit value is set.
 - `db.map`: Adds a [Prisma `@map`](https://www.prisma.io/docs/reference/api-reference/prisma-schema-reference#map) attribute to this field which changes the column name in the database
-- `graphql.read.isNonNull` (default: `false`): If you have no read access control and you don't intend to add any in the future,
+- `graphql.isNonNull.read` (default: `false`): If you have no read access control and you don't intend to add any in the future,
   you can set this to true and the output field will be non-nullable. This is only allowed when you have no read access control because otherwise,
   when access is denied, `null` will be returned which will cause an error since the field is non-nullable and the error
   will propagate up until a nullable field is found which means the entire item will be unreadable and when doing an `items` query, all the items will be unreadable.
-- `graphql.create.isNonNull` (default: `false`): If you have no create access control and you want to explicitly show that this is field is non-nullable in the create input
+- `graphql.isNonNull.create` (default: `false`): If you have no create access control and you want to explicitly show that this is field is non-nullable in the create input
   you can set this to true and the create field will be non-nullable and have a default value at the GraphQL level.
   This is only allowed when you have no create access control because otherwise, the item will always fail access control
   if a user doesn't have access to create the particular field regardless of whether or not they specify the field in the create.
@@ -30,11 +30,9 @@ export default config({
           defaultValue: true,
           db: { map: 'my_checkbox' },
           graphql: {
-            read: {
-              isNonNull: true
-            },
-            create: {
-              isNonNull: true
+            isNonNull: {
+              read: true,
+              create: true,
             },
           }
         }),