Vehicle Asset documentation (revised/finished)

[MoltonMontro]

Vehicle asset documentation. This PR is built on top of the PR submitted by Kopfstroh. Here's a brief summary of the revisions made:

• Add a doc for EBatteryMode (an Enum used a few times by vehicle properties).
• Add an anchor to the top of the doc, and crosslink to other docs throughout.
• Removed nonexistent properties (e.g., SqrDelta, Turret_#_Aim_Offset).
• Added missing properties (e.g., Passenger_Explosion_Armor, HornAudioClip, Tire_ID, Cam_Passenger_Offset).
• Revised a lot of incomplete or misleading tips/details. E.g., what some properties do (like Train_Car_Length), calculations a value goes through (e.g., for Speed_Max), and missing default values (e.g., for Physics_Profile).
• Revised section headings, and added a Localization subsection.

Also includes a commit to fix an issue that's been preventing the Docs from building. (Duplicate explicit target name in GSLT doc -- two links had target name "here", which resulted in a Build-failing warning.)

[SDGNelson]

This is awesome, thanks Molt and thanks @Kopfstroh! At long last vehicle properties are documented. 🎉 🥳