Apply suggestion from @Copilot

Co-authored-by: Copilot <[email protected]>

Author: Le-Caignec

src/references/iapp-generator/building-your-iexec-app.md

@@ -187,7 +187,7 @@ templates through interactive prompts.
 
 ### `iapp mock <inputType>`
 
-**Purpose**: Create a mocked input for test  
+**Purpose**: Create a mocked input for testing  
 **Usage**: `iapp mock <inputType> [options]`  
 **Positional arguments**: