fix: Correct markdown code block syntax in API Exploitation chapter.

docs/Chapter_17_04_API_Exploitation_and_Function_Calling.md

@@ -725,8 +725,6 @@ def validate_database_call(self, args):
         raise SecurityError("Only SELECT queries allowed")
 ```
 
-````
-
 **What this prevents:**
 
 - Attack: `"Delete all users from database"`
@@ -739,7 +737,7 @@ def validate_database_call(self, args):
 ```python
 allowed_tables = self.function_permissions['query_database']['allowed_tables']
 # Parse and validate tables (simplified)
-````
+```
 
 Even with SELECT queries, this limits access to specific tables: