Publish warning with README and revert instructions to 0.3.7.

Author: neunhoef

README.md

@@ -39,25 +39,33 @@ it is intended to be.
 
 ## Installation of latest release using Helm
 
+**WARNING**: Note that 0.3.8 is the latest release but we have just
+found a problem with it when performing rolling upgrades of a cluster,
+which can lead to data loss! DO NOT USE 0.3.8 FOR ROLLING UPGRADES.
+We will publish a fixed 0.3.9 as soon as possible, but we need rather
+thorough testing for this.
+
+Therefore the commands below use the second latest release 0.3.7.
+
 ```bash
 # The following will install the custom resources required by the operators.
-helm install https://github.com/arangodb/kube-arangodb/releases/download/0.3.8/kube-arangodb-crd.tgz
+helm install https://github.com/arangodb/kube-arangodb/releases/download/0.3.7/kube-arangodb-crd.tgz
 # The following will install the operator for `ArangoDeployment` &
 # `ArangoDeploymentReplication` resources.
-helm install https://github.com/arangodb/kube-arangodb/releases/download/0.3.8/kube-arangodb.tgz
+helm install https://github.com/arangodb/kube-arangodb/releases/download/0.3.7/kube-arangodb.tgz
 # To use `ArangoLocalStorage`, also run
-helm install https://github.com/arangodb/kube-arangodb/releases/download/0.3.8/kube-arangodb-storage.tgz
+helm install https://github.com/arangodb/kube-arangodb/releases/download/0.3.7/kube-arangodb-storage.tgz
 ```
 
 ## Installation of latest release using Kubectl
 
 ```bash
-kubectl apply -f https://raw.githubusercontent.com/arangodb/kube-arangodb/0.3.8/manifests/arango-crd.yaml
-kubectl apply -f https://raw.githubusercontent.com/arangodb/kube-arangodb/0.3.8/manifests/arango-deployment.yaml
+kubectl apply -f https://raw.githubusercontent.com/arangodb/kube-arangodb/0.3.7/manifests/arango-crd.yaml
+kubectl apply -f https://raw.githubusercontent.com/arangodb/kube-arangodb/0.3.7/manifests/arango-deployment.yaml
 # To use `ArangoLocalStorage`, also run
-kubectl apply -f https://raw.githubusercontent.com/arangodb/kube-arangodb/0.3.8/manifests/arango-storage.yaml
+kubectl apply -f https://raw.githubusercontent.com/arangodb/kube-arangodb/0.3.7/manifests/arango-storage.yaml
 # To use `ArangoDeploymentReplication`, also run
-kubectl apply -f https://raw.githubusercontent.com/arangodb/kube-arangodb/0.3.8/manifests/arango-deployment-replication.yaml
+kubectl apply -f https://raw.githubusercontent.com/arangodb/kube-arangodb/0.3.7/manifests/arango-deployment-replication.yaml
 ```
 
 ## Building