Documentated changes

Author: ewoutp

CHANGELOG.md

@@ -3,8 +3,12 @@
 - Database upgrade procedure has changed.
   It is now much more automated and can be triggered using
   an `arangodb upgrade --starter.endpoint=...` command.
+  See [Upgrading _Starter_ Deployments](./docs/Manual/Upgrading/Starter/README.md)
+  for details.
 - Added `arangodb remove starter` command to remove a machine
   from a cluster in a controlled manor.
+  See [ArangoDB Starter Removal Procedure](./docs/Manual/Administration/Starter/Removal.md)
+  for details.
 - Changed default value of `--server.storage-engine` from `mmfiles`
   to an empty string. For deployments using ArangoDB 3.3 or earlier
   the effective default is still `mmfiles`. For deployments using ArangoDB 3.4

docs/Manual/Programs/Starter/Options.md

@@ -261,6 +261,9 @@ This option only has to be specified if the standard search fails.
 Sets the storage engine used by the `arangod` servers.
 The value `rocksdb` is only allowed on `arangod` version 3.2 and up.
 
+On `arangod` version 3.3 and earlier, the default value is `mmfiles`.
+On `arangod` version 3.4 and later, the default value is `rocksdb`.
+
 - `--cluster.start-coordinator=bool`
 
 This indicates whether or not a coordinator instance should be started