Backport of Update compatibility matrix to include 1.20.x into release/1.20.x (#21851)

* backport of commit 401e15655b

* backport of commit d470792ddb

---------

Co-authored-by: Nathan Coleman <nathan.coleman@hashicorp.com>

website/content/docs/k8s/compatibility.mdx

@@ -29,6 +29,7 @@ apply to both Consul Enterprise and Consul community edition (CE).
 
 | Consul version | Compatible `consul-k8s` versions | Compatible Kubernetes versions | Compatible OpenShift versions |
 | -------------- | -------------------------------- | -------------------------------| ------------------------------|
+| 1.20.x         | 1.6.x                            | 1.28.x - 1.30.x                | 4.13.x - 4.15.x               |
 | 1.19.x         | 1.5.x                            | 1.27.x - 1.29.x                | 4.13.x - 4.15.x               |
 | 1.18.x CE      | 1.4.x                            | 1.26.x - 1.29.x                | 4.13.x - 4.15.x               |
 | 1.17.x         | 1.3.x                            | 1.25.x - 1.28.x                | 4.12.x - 4.15.x               |