Small doc addition for OLM operator plugins
@@ -75,3 +75,16 @@ To implement support for a new OLM operator plugin you need to make following ch
```
1. Implement tests verifying new OLM operator installation and validation, i.e. in [internal/bminventory/inventory_test.go](../../internal/bminventory/inventory_test.go)
1. Make sure all the tests are green
+
+## Notes about the Operator interface
+
+### Manifests generation
+A plugin can generate two distinct set of manifests, specified by the two return values of the `GenerateManifests(*common.Cluster) (map[string][]byte, []byte, error)` method. They are required to:
+
+1. Install the operator
+2. Configure the operator
+
+The first return value could be used to specify a set of manifests that will be applied directly to the control plane during the bootstrap phase. This set is usually composed by a
+manifest for creating a new namespace, a new subscription and a new operator group CR for the involved operator.
+
+The second return value it's a manifest used to configure the freshly installed operator, and it will be applied by the ```assisted-installer-controller``` job, only after the cluster have been successfully created and the OLM operators are all ready (currently the ```assisted-installer-controller``` retrieves the whole list of configurations by downloading the ```custom_manifests.json``` file fetched from the Assisted Service).
