Updated docs and created release annoucement for 1.18-4 (#343)

* Updated README for 1.18-4

* Updated index.md under docs for 1.18-4

* Added CHANGELOG for 1.18-4

* Added index.md and CRD for 1.18-4

* Added release announcement for 1.18-4

* Updated CRD for 1.18-4

* Added link to upstream release

* Update docs/contents/releases/1-18/4/release-announcement.txt

Co-authored-by: Terry Howe <terrylhowe@gmail.com>

Co-authored-by: Terry Howe <terrylhowe@gmail.com>

Author: Kirsten Schumy

README.md

@@ -25,7 +25,7 @@ Full documentation for releases can be found on https://distro.eks.amazonaws.com
 
 | Release | Manifest |
 | --- | --- |
-| 3 | [kubernetes-1-18-eks-3](https://distro.eks.amazonaws.com/kubernetes-1-18/kubernetes-1-18-eks-3.yaml) |
+| 3 | [kubernetes-1-18-eks-4](https://distro.eks.amazonaws.com/kubernetes-1-18/kubernetes-1-18-eks-4.yaml) |
 
 ### Kubernetes 1-19
 

docs/contents/index.md

@@ -118,9 +118,13 @@ Machine Images), but it does use the EKS Optimized AMI. See the project
 repository for the [EKS Optimized AMI](https://github.com/awslabs/amazon-eks-ami)
 if you are interested in the AL2 container runtime kernel version.
 
-* [EKS-D v1-19-eks-3 Version Dependencies](releases/1-19/3/index.md)
-* [EKS-D v1-19-eks-2 Version Dependencies](releases/1-19/2/index.md)
-* [EKS-D v1-19-eks-1 Version Dependencies](releases/1-19/1/index.md)
-* [EKS-D v1-18-eks-3 Version Dependencies](releases/1-18/3/index.md)
-* [EKS-D v1-18-eks-2 Version Dependencies](releases/1-18/2/index.md)
-* [EKS-D v1-18-eks-1 Version Dependencies](releases/1-18/1/index.md)
+#### EKS-D 1.19 Version Dependencies
+* [v1-19-eks-3](releases/1-19/3/index.md)
+* [v1-19-eks-3](releases/1-19/2/index.md)
+* [v1-19-eks-3](releases/1-19/1/index.md)
+
+#### EKS-D 1.18 Version Dependencies
+* [v1-18-eks-4](releases/1-18/4/index.md)
+* [v1-18-eks-3](releases/1-18/3/index.md)
+* [v1-18-eks-2](releases/1-18/2/index.md)
+* [v1-18-eks-1](releases/1-18/1/index.md)

docs/contents/releases/1-18/4/CHANGELOG-v1-18-eks-4.md

@@ -0,0 +1,36 @@
+# Changelog for v1-18-eks-4
+
+This changelog highlights the changes for [v1-18-eks-4](https://github.com/aws/eks-distro/tree/v1-18-eks-4).
+
+
+## Version Upgrades 
+
+### Kubernetes
+
+Upgraded Kubernetes from v1.18.9 to [v1.18.16](https://github.com/kubernetes/kubernetes/releases/tag/v1.18.16).
+
+### Base Image
+
+Ungraded base image (Amazon Linux 2) version to include the latest security fixes.
+
+
+## Patches 
+
+### Removed Patch
+
+* **0017-EKS-PATCH-Accept-healthy-instances-in-list-of-active.patch**
+  * Removed because these changes were cherry-picked by upstream Kubernetes and included in the version of Kubernetes 
+    used by this release of EKS-D.
+  * See upstream Kubernetes [PR #97164](https://github.com/kubernetes/kubernetes/pull/97164) for additional information.
+
+### Additional Changes to Patches
+Below are additional changes to the patches in this minor release of EKS-D. These changes are functionally immaterial 
+and do not impact the use or application of the patches.
+
+  * The two patches that came after the removed patch were renamed to keep constancy for the numbering in the patch 
+   filenames. The numbers in their filenames were decremented by one.
+    * **0018**-EKS-PATCH-Delete-leaked-volume-<...>-kno.patch --> **0017**-EKS-PATCH-Delete-leaked-volume-<...>-kno.patch
+    * **0019**-2021-25735_1_18.patch --> **0018**-2021-25735_1_18.patch
+  * Minor modifications to the patches themselves to match code changes in the upgraded Kubernetes version.
+    
+