docs: add low level api to glossary (#1523)

Author: csviri

docs/documentation/glossary.md

@@ -19,4 +19,11 @@ permalink: /docs/glossary
   the `Deployment` is the primary resource while `ReplicaSet` is one of the secondary resources
   managed by the `Deployment` controller.
 - **Dependent Resource** - a feature of JOSDK, to make it easier to manage secondary resources. A
-  dependent resource represents a secondary resource with related reconciliation logic.
+  dependent resource represents a secondary resource with related reconciliation logic.
+- **Low-level API** - a reconciler implementation without using the Dependent Resource and Workflow features.
+  Simply just implementing a logic using
+  the [`Reconciler`](https://github.com/java-operator-sdk/java-operator-sdk/blob/main/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/Reconciler.java)
+  interface. See
+  the [WebPage sample](https://github.com/java-operator-sdk/java-operator-sdk/blob/main/sample-operators/webpage/src/main/java/io/javaoperatorsdk/operator/sample/WebPageReconciler.java)
+  . See also the same logic
+  implemented using [Dependent Resource and Workflows](https://github.com/java-operator-sdk/java-operator-sdk/blob/main/sample-operators/webpage/src/main/java/io/javaoperatorsdk/operator/sample/WebPageManagedDependentsReconciler.java)