Remove older, unsupported documentation versions

Author: rjeberhard

README.md

@@ -31,7 +31,7 @@ Documentation for the operator is [available here](https://oracle.github.io/webl
 This documentation includes information for users and for developers.  It provides samples, reference material, security
 information and a [Quick Start](https://oracle.github.io/weblogic-kubernetes-operator/quickstart/) guide if you just want to get up and running quickly.
 
-Documentation for prior releases of the operator: [2.5.0](https://oracle.github.io/weblogic-kubernetes-operator/2.5/), [2.6.0](https://oracle.github.io/weblogic-kubernetes-operator/2.6/), [3.0.x](https://oracle.github.io/weblogic-kubernetes-operator/3.0/), [3.1.x](https://oracle.github.io/weblogic-kubernetes-operator/3.1/), [3.2.x](https://oracle.github.io/weblogic-kubernetes-operator/3.2/), [3.3.x](https://oracle.github.io/weblogic-kubernetes-operator/3.3/), and [3.4.x](https://oracle.github.io/weblogic-kubernetes-operator/3.4/).
+Documentation for prior releases of the operator: [3.4](https://oracle.github.io/weblogic-kubernetes-operator/3.4/).
 
 ## Backward compatibility guidelines