Add changelog for LKE release 1.12.1

Author: thorner

src/content/changelog/lke-1-12-1.md

@@ -0,0 +1,16 @@
+---
+title: Linode Kubernetes Engine v1.12.1
+date: 2021-01-11T05:00:00.000Z
+version: 1.12.1
+changelog:
+  - Linode Kubernetes Engine
+---
+
+## Added
+
+* Upgrade cluster control plane components to latest available patch version:
+  v1.17.16 and v1.18.14
+* Add support for cluster upgrades to the next available Kubernetes minor
+  version
+* Add support for full-cluster and individual node recycle
+