docs: corrects old imports (#8769)

1
`import type { Field } from 'payload/types'`
to
`import type { Field } from 'payload'`
2
`import { buildConfig } from 'payload/config'`
to
`import { buildConfig } from 'payload'`

3
```
import { SelectInput, useField } from 'payload/components/forms';
import { useAuth } from 'payload/components/utilities';
```
to
`import { SelectInput, useAuth, useField } from '@payloadcms/ui'`

4
uses `import type` for `import type { CollectionConfig } from 'payload'`

docs/authentication/overview.mdx

@@ -25,7 +25,7 @@ When Authentication is enabled on a [Collection](../configuration/collections),
 To enable Authentication on a Collection, use the `auth` property in the [Collection Config](../configuration/collection#auth):
 
 ```ts
-import { CollectionConfig } from 'payload'
+import type { CollectionConfig } from 'payload'
 
 export const Users: CollectionConfig = {
   // ...
@@ -48,7 +48,7 @@ Any [Collection](../configuration/collections) can opt-in to supporting Authenti
 To enable Authentication on a Collection, use the `auth` property in the [Collection Config](../configuration/collections):
 
 ```ts
-import { CollectionConfig } from 'payload'
+import type { CollectionConfig } from 'payload'
 
 export const Admins: CollectionConfig = {
   // ...