rm unused opensearch

formerly about to be used by graylog,
which itself has been replaced twice over

opensearch-operator/.gitignore

@@ -1 +0,0 @@
-application.yaml

opensearch-operator/README.md

@@ -1,10 +0,0 @@
-# OpenSearch operator
-
-Graylog is about to move away from ElasticSearch and OpenSearch is here to stay
-
-```
-helm repo add opensearch-operator https://opensearch-project.github.io/opensearch-k8s-operator/
-helm template opensearch-operator opensearch-operator/opensearch-operator -n opensearch-operator --version v2.6.1 > application.yaml
-kubectl create namespace opensearch-operator
-kubectl apply -n opensearch-operator -f application.yaml
-```