packages,plugins: add package documentation

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

plugins/kubernetes-backend/api-report.md

@@ -163,6 +163,4 @@ export interface ServiceAccountClusterDetails extends ClusterDetails {}
 //
 // @public (undocumented)
 export type ServiceLocatorMethod = 'multiTenant' | 'http';
-
-// (No @packageDocumentation comment for this package)
 ```

plugins/kubernetes-backend/src/index.ts

@@ -14,6 +14,12 @@
  * limitations under the License.
  */
 
+/**
+ * A Backstage backend plugin that integrates towards Kubernetes
+ *
+ * @packageDocumentation
+ */
+
 export * from './service/router';
 export * from './types/types';