add post "Build an Image Object Labeler App..." and contributor "chris-betz"

[cbetz]

Description of changes:

• add post "Build an Image Object Labeler App using AWS Amplify and React Native"
• add contributor "chris-betz"

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[cbetz]

Happy to close this PR if not useful or relevant. Just let me know, thank you!

[aspittel]

Hey @cbetz , sorry for the slow response on this - the project is no longer being maintained but will be replaced with something new soon. Thank you so much for writing about amplify and being a member of the community!

[cbetz]

No problem! Excited to see what's coming next.