Highlight ZDRayInfo being a requirement for lightmaps, add VKDoom to …

…the readme

README.md

@@ -1,5 +1,5 @@
 
-# ZDRay baking utility for GZDoom
+# ZDRay baking utility for VKDoom/GZDoom
 
 ZDRay is a node and lightmap generator for GZDoom. ZDRay is intended as a drop-in replacement for zdbsp, with the additional feature that it can also bake lightmap lights. Once ZDRay has processed the level WAD it is ready to be used by GZDoom.
 
@@ -9,6 +9,8 @@ The ray tracing code has been completely rewritten since. ZDRay has two paths fo
 
 ## ZDRay Usage
 
+**ATTENTION: You MUST place down a ZDRayInfo actor somewhere in the map for the lightmaps to appear at all!**
+
 <pre>
 Usage: zdray [options] sourcefile.wad
   -m, --map=MAP            Only affect the specified map