docs: Drop some old compat notices that no longer apply

[jonathan-innis]

Fixes #N/A

Description

There are some compatibility notices that are either for versions of K8s that we don't formally document that we support anymore (because they are quite old at this point) OR that are not outright supported by the latest versions of Karpenter (like webhooks)

How was this change tested?

Does this change impact docs?

• Yes, PR includes docs updates
• Yes, issue opened: #
• No

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[netlify]

✅ Deploy Preview for karpenter-docs-prod ready!

Name	Link
🔨 Latest commit	b6695fd
🔍 Latest deploy log	https://app.netlify.com/sites/karpenter-docs-prod/deploys/67c92f4f0ff4390008c39c21
😎 Deploy Preview	https://deploy-preview-7854--karpenter-docs-prod.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[coveralls]

Pull Request Test Coverage Report for Build 13691757070

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.01%) to 67.126%

---

Files with Coverage Reduction	New Missed Lines	%
pkg/providers/instance/instance.go	1	91.97%

Totals
Change from base Build 13691560594:	-0.01%
Covered Lines:	6767
Relevant Lines:	10081

---

💛 - Coveralls

[rschalo]

LGTM