Explain the changes

1. The capabilities annotation indicates the maturity level of the operator in the OLM
2. more details here: https://sdk.operatorframework.io/docs/overview/operator-capabilities/#level-2---seamless-upgrades

Issues: Fixed #xxx / Gap #xxx

1. https://bugzilla.redhat.com/show_bug.cgi?id=2303820

Testing Instructions:

1. generate noobaa CSV. e.g.:

   make gen-odf-package csv-name="noobaa-operator.csv" core-image="noobaa/noobaa-core:5.10.0" db-image="centos/postgresql:12" operator-image="noobaa/noobaa-operator:5.10.0" obc-crd="none" psql-12-image="ttt"
   

2. check that the generated CSV has the capabilities annotation with Seamless Upgrades values

• Doc added/updated
• Tests added