Ask contribution to Tensorflow addons for general scope utils, loss, layers, ops

[bhack]

As we have just refreshed the model repo as model garden I would enforce the contributions policies of generale use (or already established in literature utils, losses, layers, ops to be contribute more systematically in Tensorflow/addons instead to be embedded or duplicated in the model repos.
E.g:
tensorflow/addons#361 (comment)
tensorflow/addons#1364 (comment)
tensorflow/addons#1366
tensorflow/addons#1226 (comment)
tensorflow/addons#1226 (comment)

/cc @ewilderj @facaiy @seanpmorgan

Policies to be enforced with a PR

https://github.com/tensorflow/models/blob/master/CONTRIBUTING.md
https://github.com/google-research/google-research/blob/master/CONTRIBUTING.md
https://github.com/google/automl/blob/master/CONTRIBUTING.md

[bhack]

/cc @dynamicwebpaige If she is interested.

[bhack]

See also the approved RFC https://github.com/tensorflow/community/blame/master/rfcs/20190802-model-garden-redesign.md#L60-L61

[bhack]

I will add in the target contributions repos the new keras-cv and keras-nlp.

[bhack]

E.g. See tensorflow/models#8962 (review)

[theadactyl]

@bhack still interested in this?

[bhack]

In general this is a still valid topic but:

• For TF Addons we could close this as we have:
  TF Addons CV components keras-team/keras-cv#74
  tf.addons.text ops coverage keras-team/keras-hub#11

• More in general for the ecosystem I could add a reference to this ticket in Add a standard CONTRIBUTING.md template #384