update azure plugins documentation

[VinozzZ]

What does this change

Update doc file for the azure plugins update getporter/azure-plugins#41

What issue does it fix

Part of #1027

Notes for the reviewer

Only merge after the azure plugin update PR has merged

Checklist

• Did you write tests?
• Did you write documentation?
• Did you change porter.yaml or a storage document record? Update the corresponding schema file.
• If this is your first pull request, please add your name to the bottom of our Contributors list. Thank you for making Porter better! 🙇‍♀️

Reviewer Checklist

• Comment with /azp run test-porter-release if a magefile or build script was modified
• Comment with /azp run porter-integration if it's a non-trivial PR

[carolynvs]

LGTM!

Heads up that I am holding off on merging any docs related to these plugin changes until we are ready to release everything. So once the plugins have new releases available and we've cut a new release of Porter with all the plugin changes, then I'll merge so that people don't get confused about what's available.