Update the Docs Maintainer Guide

[marcduiker]

Describe the issue
The guide has some outdated information:

• https://docs.dapr.io/contributing/docs-contrib/maintainer-guide/#pull-in-sdk-doc-updates Can be removed
• azd login is now azd auth login
• Add a remark that the docs default branch needs to be updated to the latest version.
• Remove Next steps section at the end

URL of the docs
https://docs.dapr.io/contributing/docs-contrib/maintainer-guide/