[Doc] OverrideDetectedTotalMemory (ArangoDB Env ARANGODB_OVERRIDE_DETECTED_TOTAL_MEMORY) documentation (#1258)

Author: jwierzbo

docs/design/README.md

@@ -5,6 +5,7 @@
 - [Metrics](./metrics.md)
 - [Kubernetes Pod name versus cluster ID](./pod_name_versus_cluster_id.md)
 - [Resource & labels](./resource_and_labels.md)
+- [Resource Management](./resource_management.md)
 - [Scaling](./scaling.md)
 - [Status](./status.md)
 - [Upgrading](./upgrading.md)

docs/design/resource_management.md

@@ -0,0 +1,22 @@
+# Resource Management
+
+## overrideDetectedTotalMemory
+
+The `spec.<group>.overrideDetectedTotalMemory` flag is an option that allows users to override the total memory available to the ArangoDB member 
+by automatically injecting `ARANGODB_OVERRIDE_DETECTED_TOTAL_MEMORY` ENV variable into the container with the value of `spec.<group>.resources.limits.memory`.
+
+Sample:
+
+```yaml
+apiVersion: database.arangodb.com/v1
+kind: ArangoDeployment
+metadata:
+  name: cluster
+spec:
+  mode: Cluster
+  dbservers:
+    overrideDetectedTotalMemory: true
+    resources:
+      limits:
+        memory: 1Gi
+```