Update README with project structure details

Clarified project structure and its components.

Signed-off-by: Fabiana  ⚡️ Campanari <113218619+FabianaCampanari@users.noreply.github.com>

Author: FabianaCampanari

README.md

@@ -314,8 +314,9 @@ The [**second subproject**]() in the briefing explicitly requires building an AP
 > [!IMPORTANT]
 > 
 >  ⚠️ Projects are structured to be publicly documented and version-controlled. <br>
-> 
-
+>
+> Together, **Stage 1 + Stage 2** form the official **extension project agreed with the professor**, covering APIs, data pipelines, SQL design and RESTful Web Services.<br>
+>
 
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