platform support generated

This is an experiment of what generated target tier documentation could look like.

See https://github.com/Nilstrieb/target-tier-docs-experiment for the source. The README of the repo contains more information about the motivation and benefits.

Targets of interest with information filled out are any tvos targets like aarch64-apple-tvos and powerpc64-ibm-aix.

But as you might notice, all targets are actually present with a stub :3.