Add OLM upgrade instructions (#141)

Author: ciarams87

docs/upgrades.md

@@ -3,6 +3,22 @@
 Release 0.3.0 includes a major upgrade of the Operator-SDK which has resulted in a number of changes in the layout of the project
 (see [the operator-sdk docs](https://sdk.operatorframework.io/docs/building-operators/golang/migration/) for more information).
 
+## OLM upgrade - 0.2.0 to 0.3.0
+
+**Note: The `nginx-ingress-operator` supports basic install only - we do not support auto-updates. When you are installing the Operator using the OLM, the auto-update feature should be disabled to avoid breaking changes being auto-applied.**
+
+### 1. Uninstall the existing 0.2.0 operator
+
+Uninstall the operator using the web console - see [the OCP documentation for details](https://access.redhat.com/documentation/en-us/openshift_container_platform/4.6/pdf/operators/OpenShift_Container_Platform-4.6-Operators-en-US.pdf).
+
+### 2. Reinstall the latest version of the operator
+
+Install the latest version of the Operator following the steps outlined in [OpenShift installation doc](./openshift-installation.md).
+
+### 3. Upgrade the existing ingress controller deployments
+
+Upgrade to the latest 1.12.0 Ingress Controller image - see the release notes [here](https://docs.nginx.com/nginx-ingress-controller/releases/#nginx-ingress-controller-1-12-0)
+
 ## Manual upgrade - 0.2.0 to 0.3.0
 
 ### 1. Deploy the new operator