Outdated --kubernetes-version references

[philip]

The latest Getting Started: Operator suggests installing an oldish and specific version of Kubernetes:

minikube start --kubernetes-version=v1.19.16 --cpus=4 --memory=4000 --disk-size=32g

References:

content/en/docs/14.0/get-started/operator.md
  minikube start --kubernetes-version=v1.19.16 --cpus=4 --memory=4000 --disk-size=32g
content/en/docs/13.0/get-started/operator.md
  minikube start --kubernetes-version=v1.19.16 --cpus=4 --memory=4000 --disk-size=32g
content/en/docs/12.0/get-started/operator.md
  minikube start --kubernetes-version=v1.19.16 --cpus=4 --memory=4000 --disk-size=32g
content/en/docs/11.0/get-started/operator.md
  We recommend using Kubernetes 1.14, as this is a common denominator across public clouds:
  minikube start --kubernetes-version=v1.14.10 --cpus=8 --memory=11000 --disk-size=50g

There's also a similar (but older) reference in vitess.git's example operator readme:

examples/operator/README.md
  minikube start --cpus=8 --memory=11000 --disk-size=50g --kubernetes-version=v1.19.5

Suggestion is to either:

A. Remove the --kubernetes-version parameter and instead rely upon the prerequisites documentation it links to.

B. Or only add --kubernetes-version to older versioned docs if the latest stable isn't supported, and if it won't change.

Option (B) risks becoming outdated (e.g., examples/operator/README.md) although --kubernetes-version=v1.19.16 may be appropriate for docs/11.0/ and docs/12.0/ today, although the prerequisites matrix is missing v11.0 so I'm not sure.

FWIW I prefer (A) to avoid future doc maintenance and bug reports like this. Regardless, I can create a PR if folks agree upon a solution as I'm not familiar enough with Vitess to know for certain.

Related: I hoped --kubernetes-version= didn't require a patch version but it appears required, else the likes of --kubernetes-version=v1.19 would be possible with (B).

[deepthi]

@GuptaManan100 @frouioui @Verolop what would you recommend?

[frouioui]

I like option A as it has a single point of maintenance. We would only need to update the compatibility table of the vitess operator. However, as a user, I think it is nice to just be able to copy/paste command lines from the getting started guide.

I think we should remove the instructions in examples/operator/README.md and instead link to the documentation. That way we can have all the documentation regarding the getting started guide in a single place.

I lean more towards an option between A and B where we would continue updating the vitess operator compatibility table, and start updating the getting started guide with the proper kubernetes versions. But I do not have strong opinions.