Change api version

[akihikokuroda]

Changes

This is the step 1 of #499
Change the API version of

1. docs/create-ingress.yaml
2. docs/create-webhook.yaml
   to v1beta1

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[akihikokuroda]

/uncc @iancoffey
/cc @dibyom

[ncskier]

With v1beta1, $(inputs.params. becomes $(params.. So, I think you'll have to update that in a few spots.

[akihikokuroda]

Thanks for review. I'll fix them.

[ncskier]

Thanks for the updates
/lgtm

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