Add plugin to krew

[timebertt]

Usually, one would install new kubectl plugins via krew.

The history plugin should be added to krew to make it easy to discover, install, and update.

For adding the plugin to the krew index, see https://krew.sigs.k8s.io/docs/developer-guide/release/new-plugin/
Before, the plugin can be added, a first version must be released.

For setting up automated krew index updates, see https://krew.sigs.k8s.io/docs/developer-guide/release/automating-updates/ / https://github.com/rajatjindal/krew-release-bot
There is also a goreleaser integration for this, but it seems less popular.

[timebertt]

Unfortunately, the history plugin name is already taken in the krew index.
It seems like somebody had the same plugin idea while I was keeping my initial work in a private repo for almost a year without finishing it 🙈
kubernetes-sigs/krew-index#3605

[timebertt]

Let's rename this repository/plugin to kubectl-revisions, which is not taken in the krew index yet.
revisions plays nicely with the subcommands, it is less catchy though.