Publish semver-stable 1.0

Follow-up to
https://github.com/bazel-contrib/rules_go/issues/2572#issuecomment-926733296

The main README https://github.com/bazel-contrib/rules_go#overview says:

> The rules are in the beta stage of development

However we all know that many users are taking a production dependency on rules_go and rely on the ability to upgrade. It would be nice to create a 1.0 milestone to collect the blocking issues/PRs for breaking changes the maintainers have in mind.

Note that rules_python just went 1.0.

Start with the main README's Overview section and the follow-up discussion in rules_go issue 2572, especially the linked comment. Review the repository's open blocking issues and pull requests for breaking changes; done means the maintainers have agreed on the 1.0 milestone and its release criteria.

Written by the indexing model from the issue text.