fix file path in md

Author: Bleidhu

docs/database_specification.md

@@ -8,7 +8,7 @@ Szymon Rybski
 
 # Diagram bazy danych
 
-![diagram](./images/diagram.png)
+![diagram](./docs/images/diagram.png)
 
 [diagram w wersji svg](https://bleidhu.github.io/Introduction__To_Databases_2024_AGH_Project/images/diagram.svg)