Document properties used by the package (#14)

* Document properties used by the package

* Update README.md

---------

Co-authored-by: Igor Lukanin <[email protected]>

Author: AvilaJulio

README.md

@@ -35,4 +35,30 @@ Run tests:
 
 ```sh
 pdm run test
-```
+```
+
+## Preprocessing the `manifest.json` file
+
+In case of a massive manifest file, it can be preprocessed for optimal performance. The `cube_dbt` package only reads the `nodes` dictionary where `resource_type` is `model`.
+Here's a list of all keys used by the `cube_dbt` package:
+
+``` 
+- nodes
+  - name
+  - path
+  - description
+  - config
+    - materialized
+    - tags
+  - resource_type
+  - database
+  - schema
+  - alias
+  - relation_name
+  - columns
+    - name
+    - description
+    - data_type
+    - meta
+    - tags
+```