Add explanations of textures & player api usage, non-function sounds, and some minor touch-up of docs (#55)

doc/textures.md

@@ -1,3 +1,20 @@
 # Textures API
 
-consult `/src/texture/minetest.lua` at this time
+## Usage
+
+To use a texture in your mod, find the texture you want by looking at one of
+the files in `/src/texture`, and append its path to `xcompat.textures`.
+
+If a texture isn't supported for the current game, xcompat creates a solid 
+color texture using texture modifiers as a fallback, ensuring compatibility.
+
+## Example
+
+| Path                                | Result in Minetest Game      |
+| -                                   | -                            |
+| xcompat.textures.wool.white         | `"wool_white.png"`           |
+| xcompat.textures.wood.apple.planks  | `"default_wood.png"`         |
+| xcompat.textures.wood.jungle.leaves | `"default_jungleleaves.png"` |
+| xcompat.textures.glass.pane         | `"default_glass.png"`        |
+
+For games like Minetest and Mineclonia, see the file `/src/textures/minetest.lua`.