This commit:
- Adds config for building Windows installers
- Adds an action for fetching exe files built by goreleaser
- Adds an action for building Windows installers
- Adds an action for adding MSI files to an existing GH release
- Adds MSI signing to our release flow
- Disables homebrew formula bumping for prereleases
- Allows the release asset copying action to copy windows assets
`make site-docs`:
1. checks out the `gh-pages` branch into the `site/` directory;
2. regenerates `.md` help pages using Cobra;
3. commits and publishes updates.
