[docs] display beta warning and decorator info

[maximearmstrong]

Summary & Motivation

Same as #25362 but for the new beta decorator introduced in #26748

[maximearmstrong]

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• [docs-beta] Map API lifecycle flags to style levels for docs beta #26846
• [docs] display beta warning and decorator info #26821 👈 (View in Graphite)
• [docs] display preview warning and decorator info #26819
• master

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[github-actions]

Deploy preview for dagster-docs ready!

Preview available at https://dagster-docs-7w4aq188v-elementl.vercel.app
https://maxime-ad-759-add-beta-docs.dagster.dagster-docs.io

Direct link to changed pages:

• https://dagster-docs-7w4aq188v-elementl.vercel.app
  https://maxime-ad-759-add-beta-docs.dagster.dagster-docs.io/about/releases

[github-actions]

Deploy preview for dagster-docs-beta ready!

Preview available at https://dagster-docs-beta-32ir2hfh9-elementl.vercel.app

Direct link to changed pages:

[cmpadden]

@maximearmstrong do we need to make any changes for the new docs as well? For example, I recall association a color, experimental -> warning in the MDX builder here:

https://github.com/dagster-io/dagster/blob/master/docs/sphinx/_ext/sphinx-mdx-builder/sphinxcontrib/mdxbuilder/writers/mdx.py#L950

Which is then styled in the CSS here:

https://github.com/dagster-io/dagster/blob/master/docs/docs-beta/src/styles/custom.scss#L622-L653

[cmpadden]

Approved.

I left a comment regarding the styling for Docusaurus, which we can address in a follow-up PR (if not already addressed).