Merge branch 'velero_arch_docs' into 'master'

[skip ci]/adding architecture document for velero

Closes platform-one/big-bang/apps/cluster-utilities/velero#27

See merge request platform-one/big-bang/bigbang!1927

charter/packages/velero/Architecture.md

+# Velero
+
+## Overview
+
+Velero is an open source tool to safely backup and restore, perform disaster recovery, and migrate Kubernetes cluster resources and persistent volumes.
+
+## Big Bang Touch Points
+
+```mermaid
+graph TB
+
+  subgraph "Velero"
+    velero
+  end      
+
+  subgraph "Metrics"
+    velero --> prometheus
+  end
+
+  subgraph "Object Storage"
+    velero --> minio/s3
+  end
+```
+
+### Architecture: 
+- [How Velero works](https://velero.io/docs/main/how-velero-works/)
+
+### Storage
+
+Data from velero is stored in object storage and configuration is based upon the [provider](https://repo1.dso.mil/platform-one/big-bang/apps/cluster-utilities/velero/-/blob/main/chart/values.yaml#L226). 
+
+### Istio Configuration
+
+Istio is disabled in the velero chart by default and can be enabled by setting the following values in the bigbang chart:
+
+```yaml
+istio:
+  enabled: true
+```
+
+These values get passed into the velero chart [here](https://repo1.dso.mil/platform-one/big-bang/apps/cluster-utilities/velero/-/blob/main/chart/values.yaml#L477). 
+
+## High Availability
+
+Velero does not have configurations for high availability.
+
+## Single Sign on (SSO)
+
+None. This service doesn't have a web interface.
+
+## Licensing
+
+[Apache 2.0 License](https://github.com/vmware-tanzu/velero/blob/main/LICENSE)
+
+## Dependencies
+
+Velero requires an object storage service available with the bucket details pre-configured. This can be block storage from block storage from AWS, Azure or other providers. `minio` and `miniooperator` can be enabled to provide this storage local to the cluster under the `addon` packages.
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