docs(messaging): add use_frameworks to notification images Podfile code snippet (#7745)

* Update ios-notification-images.md

Adding:
```
  use_frameworks! :linkage => :static
```

Because we use it on our main target and it solve this error:

```
[!] Unable to integrate the following embedded targets with their respective host targets (a host target is a "parent" target which embeds a "child" target like a framework or extension):

- XXX (true) and ImageNotification (false) do not both set use_frameworks!.
```

* chore: Update ios-notification-images.md

* Update docs/messaging/ios-notification-images.md

---------

Co-authored-by: Mike Hardy <[email protected]>

Author: eidan66

docs/messaging/ios-notification-images.md

@@ -33,7 +33,8 @@ Ensure that your new extension has access to Firebase/Messaging pod by adding it
 
 ```Ruby
 target 'ImageNotification' do
-  pod 'Firebase/Messaging', '~> VERSION_NUMBER' # eg 6.31.0
+  use_frameworks! :linkage => :static
+  pod 'Firebase/Messaging'
 end
 ```