Re-add support for Kubernetes versions <= v1.23

[pega-talba]

In k8s-wait-for version 2.0, support was dropped for Kubernetes versions 1.23 and earlier. (See https://github.com/groundnuty/k8s-wait-for/releases/tag/v2.0 and #60)

After reviewing the code, it would be simple to continue to support earlier versions. Because we do not care about the Ready value, we do not need to explicitly capture the digit; instead, we can capture the whole (0 Ready) string zero or one times. We then ignore the captured value, as we do today.

I do appreciate the desire to push people to the latest releases of Kubernetes, but in this case, I believe the extra code required is minimal. It also this simplifies our ability to use the project when we cannot reliably know what k8s version is being used, and prevents people from being locked on k8s-wait-for 1.x.

Changes:

• Updated the regular expression used by sed, to capture the full Ready statement
• Updated README to account for this change, as consumers would no longer need to use k8s-wait-for 1.x
• Fixed comment typos