README: update / drop "releasing a new version of docs" section

[chalin]

Since #93, I don't think that the following text from the README.md is accurate anymore, right @nate-double-u?

Releasing a new version of the etcd documentation

In order to add documentation for a version of etcd, you need to:

• Navigate to the etcd-io/etcd repo and checkout the tag for the version, for example git checkout v3.3.12.

• Copy the Documentation directory from the main etcd repo into the content/docs directory of this repository, renaming the directory to match the version. Here's an example for (non-existing) version 4.3.2:

  cp -rf /path/to/etcd-io/etcd/Documentation /path/to/etcd-io/website/content/docs/v4.3.2

• In the _index.md file at the root of the new directory, update the title metadata to reflect the new version. The title should read etcd version <new-version>.

• Add the version to the params.versions.all array in the config.toml configuration file.

• If the version is meant to be the latest version of etcd, change the params.versions.latest parameter to the desired new version.

• Submit a pull request with the changes.

[nate-double-u]

I agree, we'll need to update the README - i've added this issue to our omni-issue #134

[chalin]

IMHO, at least part of this should be fixed on the main branch.