Enhance external sensors documentation.

[Viralpanchal7899]

Reference issue

fix issue #1160: #1160

What does this implement/fix?

Adds basic information about some external sensors which were "TBD" in the document.

Additional information

CheckList

• Did you add an unittest for your new example or defect fix?
• Did you add documents for your new example?
• All CIs are green? (You can check it after submitting)

[Copilot]

Pull Request Overview

This pull request enhances the external sensors documentation by replacing placeholder TBD text with detailed descriptions and references.

• Updated the introduction text formatting for clarity
• Replaced the TBD text for Radar Sensors with a detailed explanation
• Added a Wikipedia references section for further reading

Comments suppressed due to low confidence (2)

docs/modules/12_appendix/external_sensors_main.rst:60

• [nitpick] Consider revising the indentation of the nested bullet list under the 'Wikipedia articles' header to ensure proper reStructuredText rendering. Consistent one-level indentation for sub-bullets can improve readability.

- Wikipedia articles:

docs/modules/12_appendix/external_sensors_main.rst:23

• [nitpick] The updated Radar sensor description is clear; consider ensuring similar levels of detail and style consistency across all sensor sections for a uniform documentation style.

Radar measures distances using radio waves, commonly referred to as Radio Detection and Ranging (RADAR). It operates by transmitting radio signals towards an object and calculating the distance based on the time it takes for the reflected waves to return, using the speed of radio waves as a constant. 

[AtsushiSakai]

LGTM. Thank you!!