Update the Kubernetes support matrix (#2471)

Signed-off-by: Nick Young <[email protected]>

site/_resources/kubernetes.md

@@ -9,19 +9,21 @@ Contour utilizes [client-go][1] to watch for resources in a Kubernetes cluster.
 Since Kubernetes is backwards compatible with clients, older client-go versions will work with many different Kubernetes cluster versions.
 The `client-go` package includes a [compatibility matrix][2] as to what Kubernetes API versions are supported with the version of client-go.  
 
-## Supported Kubernetes versions
-
-| Kubernetes version | Contour v1.0.0 | Contour v1.0.1 | Contour v1.1.0 | Contour v1.2.0 | Contour v1.2.1 |
-| ------------ | :-----------: | :-----------: | :----------: | :--------: |
-| 1.13.x | Supported | Supported | Supported | Not Supported<sup>1</sup> | Not Supported<sup>1</sup> |
-| 1.14.x | Supported | Supported | Supported | Not Supported<sup>1</sup> | Not Supported<sup>1</sup> |
-| 1.15.x | Supported | Supported | Supported | Supported | Supported |
-| 1.16.x | Not Supported<sup>1</sup>  | Not Supported<sup>1</sup>  | Not Supported<sup>1</sup> | Supported |  Supported |
-| 1.17.x | Not Supported<sup>1</sup>  | Not Supported<sup>1</sup>  | Not Supported<sup>1</sup> | Supported | Supported |
+It's important to note that since Contour consumes a small number of quite stable Kubernetes APIs, most Kubernetes versions most likely will not have issues, however, the client-go package does not guarantee compatibility.
 
-### Notes
+## Supported Kubernetes versions
 
-1. It's important to note that since Contour consumes a small number of quite stable Kubernetes APIs, most Kubernetes versions most likely will not have issues, however, the client-go package does not guarantee compatibility.
+| Contour Version | Kubernetes Version        |
+| --------------- | :------------------- |
+| master          | 1.18, 1.17, 1.16   |
+| 1.4.0           | 1.17, 1.16, 1.15   |
+| 1.3.0           | 1.17, 1.16, 1.15   |
+| 1.2.1           | 1.17, 1.16, 1.15   |
+| 1.2.0           | 1.17, 1.16, 1.15   |
+| 1.1.0           | 1.15, 1.14, 1.13   |
+| 1.0.1           | 1.15, 1.14, 1.13   |
+| 1.0.0           | 1.15, 1.14, 1.13   |
+{: class="table thead-dark table-bordered"}
 
 [1]: https://github.com/kubernetes/client-go
 [2]: https://github.com/kubernetes/client-go#compatibility-matrix