[REFACTOR] Updated wing design and c++ modularization doc and added new documentation for airfoils and endnode + placeholder for pyavl- and pyavlunicadopackage

Description

Refactored and added different documentations to the documentation page

Related Issue(s)

• Closes #27 (closed)

Other Changes

• N.A.

Screenshots/Logs

Testing Instructions

1. [Step 1: Checkout branch]
2. [Step 2: Run mkdocs serve + have a look at documentation for modularization description, wing design, airfoils lib, and endnode.h + index page for libraries documentation]

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

• N.A.