docs: add probationary step to Experimental GEP phase

[shaneutt]

What type of PR is this?

/kind documentation
/kind gep

What this PR does / why we need it:

To better imitate upstream Kubernetes, we need to enact "probationary periods" for GEPs during the Experimental phase.

This will help us:

• avoid GEPs spending inordinately long times in the Experimental phase without forward momentum
• better establish and enforce graduation criteria for GEPs
• better indicate to implementations that unfinished Experimental features may be removed in future releases

Additionally this removes our old "quick start" section of the enhancement page on the website in favor of a "how to", the main reason for this being we want to consult with community members before GEPs are created so that we can help contributors avoid frustration and pitfalls.

[k8s-ci-robot]

Adding the "do-not-merge/release-note-label-needed" label because no release-note block was detected, please follow our release note process to remove it.

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[robscott]

Thanks @shaneutt!

[k8s-ci-robot]

Adding the "do-not-merge/release-note-label-needed" label because no release-note block was detected, please follow our release note process to remove it.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[robscott]

Thanks @shaneutt! This LGTM other than a broken link. Will leave some time for someone else to review, but no blockers from me.

/cc @arkodg @kflynn @sunjayBhatia @youngnick
/approve

[kflynn]

I left two nits that are not meant to be blocking -- thanks for putting this together, @shaneutt, looks good! 🙂

[kflynn]

OK, let's maybe talk about a recommended time later -- ship it!! 🙂

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kflynn, robscott, shaneutt

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[shaneutt]

OK, let's maybe talk about a recommended time later -- ship it!! slightly_smiling_face

Oh I'm sorry, I added a recommended time of 6 months did I stomp all over? Take a look at the new recommended time that's in there, and comment whether that meets your criteria or whether you think there's more to do here?

/hold

[kflynn]

@shaneutt uhhhh yeah, turns out I just couldn't read or something. 🤦‍♂️ Hit it!! Looks good from here. 🙂

/lgtm

[shaneutt]

Ok, no worries thank you!

/unhold