Adds underline for MT

Description

Provide a concise explanation of the changes made in this merge request.

Related Issue(s)

• Closes #[feature issues]
• Fixes #[bug report issue]
• Resolves #[any other issues]

Other Changes

• [Mention refactoring, tests, etc.]

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Testing Instructions

1. [Step 1: How to test]
2. [Step 2: Expected outcome]
3. [Step 3: Additional steps if required]

Developer Checklist

• Code has been tested locally and/or in pipeline.
• (if applicable) documentation updated.
• (if applicable) impact of new dependencies reviewed and included in project.
• Merge conflicts resolved with the target branch.

Additional Notes

Add any information reviewers should focus on, e.g., specific files, functions, or changes of interest.

docs/documentation/libraries/engine/index.md

@@ -2,10 +2,10 @@
 
 The `_engine_` library serves as the core analysis tool for engine data within UNICADO. It provides access to all possible engine data for every tool in UNICADO. The data can be fixed for an engine or at a given operating point. The data output depends on various factors such as the scale factor and power and bleed offtakes from the engine. The primary objective is to establish a **single source of truth** for engine data retrieval.
 
-## Role in `propulsionDesign`
-Within the `propulsionDesign` module:
+## Role in `propulsion_design`
+Within the `propulsion_design` module:
 - Engines for the aircraft are selected, and their respective files are copied to the engine directory.
-- The **scale factor** is calculated, determining how the engine's thrust is adjusted to meet aircraft requirements (refer to the `propulsionDesign` documentation).
+- The **scale factor** is calculated, determining how the engine's thrust is adjusted to meet aircraft requirements (refer to the `propulsion_design` documentation).
 
 The `engine` library applies this scale factor, ensuring that aircraft parameters can be accessed without further manual adjustments.
 
@@ -18,7 +18,7 @@ The engine data is stored in:
   - **Altitude**
   - **Engine power setting**  
 
-> **Note:** The data in these files is **raw and unscaled**. The only modification made in `propulsionDesign` is to the fuel flow CSV file, reflecting user-defined efficiency improvements.
+> **Note:** The data in these files is **raw and unscaled**. The only modification made in `propulsion_design` is to the fuel flow CSV file, reflecting user-defined efficiency improvements.
 
 ## Functionality of the `engine` Library
 The library is responsible for:
@@ -30,7 +30,7 @@ The library is responsible for:
 ### Factors Affecting Engine Performance
 The `engine` library incorporates the following factors, either by default or as optional parameters:
 
-- **Scale factor** from `propulsionDesign`
+- **Scale factor** from `propulsion_design`
 - **Temperature variations** (non-ISA standard conditions)
 - **Engine derating**
 - **Bleed air extraction** (for turbofan engines)