What are some of the tooling options out there that can help the Platform team document APIs, SDKs, How-to Guides, and any supporting documentation for application developers? Heard about Backstage, but like to learn about how others manage a dev portal.

We use a mix of confluence and mkdocs, but if i was going to pick something other than the backstage tech docs it probably would be https://docusaurus.io/ setup with a gitlab pipeline for publishing.

Thanks . Will take a look at docusauraus

AsciiDoc!

We're transitioning to Backstage. Before that it was spread out across Confluence and GitHub