merge community and enterprise docs (#27)

# Summary

- removes docs which purely MCO operator based
- moves all docs to root docs folder

Author: nammn

docs/investigation/pod-is-killed-while-agent-restores.md

@@ -4,7 +4,6 @@
 
 - [Contribute to the MongoDB Kubernetes Operator](contributing.md)
 - [MongoDB Community Kubernetes Operator Architecture](architecture.md)
-- [Install and Upgrade the Community Kubernetes Operator](install-upgrade.md)
 - [Deploy and Configure MongoDBCommunity Resources](deploy-configure.md)
 - [Configure Logging of the MongoDB components](logging.md)
 - [Create Database Users](users.md)

mongodb-community-operator/docs/README.md renamed to docs/mongodbcommunity/README.md

@@ -1,6 +1,6 @@
-# MongoDB Community Kubernetes Operator Architecture
+# MongoDB Kubernetes Operator Architecture
 
-The MongoDB Community Kubernetes Operator is a [Custom Resource Definition](https://kubernetes.io/docs/concepts/extend-kubernetes/api-extension/custom-resources/) and a [Controller](https://kubernetes.io/docs/concepts/architecture/controller/).
+The MongoDB Kubernetes Operator contains multiple [Custom Resource Definitions](https://kubernetes.io/docs/concepts/extend-kubernetes/api-extension/custom-resources/) and is a [Controller](https://kubernetes.io/docs/concepts/architecture/controller/).
 
 ## Table of Contents