Add GitHub Action to automatically publish docs (#1350)
Add GitHub Action to automatically publish docs (#1350)

This commit adds a GitHub action to automatically publish doc
changes to the `gh-pages` branch, which will be rendered nicely
on https://goole.google.io/iree. This includes both docs directly
checked into the docs/ directory and docs auto-generated from
TableGen definitions. For now the former only contains IREE
Design Roadmap; the hope is to refresh existing docs and publish
them one by one.
google/iree,iree-org/iree,iree-org/iree,iree-org/iree,iree-org/iree,google/iree,google/iree,iree-org/iree,google/iree,google/iree,iree-org/iree,google/iree,google/iree,iree-org/iree