Created Track drawers, RTDs and vehicle types (markdown)

Track-drawers,-RTDs-and-vehicle-types.md

@@ -0,0 +1,12 @@
+OpenRCT2 has roughly three layers when dealing with rides.
+
+1. A “track drawer” is code that draws a track style. This track style is sometimes shared.
+2. RTDs (Ride Type Descriptors) are the most visible to the user. These are the types listed in the New Ride dialog, in the cheat dropdown where you can change the ride type, and in the left column of the ride vehicles in the Object Selection.
+3. Vehicle types consist of trains for tracked rides, and reskins of flat rides. Examples include the Double Decker Carrousel or the Corkscrew Trains. Preview images are also located here.
+
+The amount of overlap sometimes makes it hard to distinguish the three. A complicating factor is that one track drawer may be used by multiple RTDs. The converse is also true: some RTDs have different multiple different track styles that the player can choose between.
+
+Examples:
+- The RTDs for Twister RC, Vertical Drop C and Flying RC use the same track drawer, just with different supports.
+- The RTD for the Water Coaster uses both the Junior RC track drawer and the Splash Boats track drawer.
+- The RTD for the dinghy slide uses two track drawers, one for regular track and one for covered track.