Slightly better planet icon

tools/src/mindustry/tools/IconConverter.java

@@ -10,6 +10,14 @@ public class IconConverter{
     float width, height;
 
     public static void main(String[] __){
+        /*
+        Process for adding an icon to the font:
+        1. Have an SVG ready, possibly created with this tool.
+        2. Go to Fontello and load the config.json from core/assets-raw/fontgen/config.json
+        3. Drag the SVG in.
+        4. Export the config and font file, replace the old config.
+        5. Take the font (ttf) from the zip, open it in FontForge, and merge it into font.woff and icon.ttf. Usually, you would do view -> go to (the 0x unicode index).
+        **/
 
         Log.info("Converting icons...");
         Time.mark();