Some updates for the docu

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.]

Screenshots/Logs

Attach screenshots or log outputs if applicable.

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

+# Introduction {#mainpage}
+PENIS
\ No newline at end of file