make the build script use 'include' statement instead of a hard-coded '.asm' file list

readme.md

@@ -43,7 +43,10 @@ Bundle all `.asm` and `.ppm` files and output the (optionaly minified) result.
 
 Usage example:
 ```sh
-./build.ts --minify > pacman.asm
+./build.ts --minify main.asm > pacman.asm
+
+# To beforehand convert all ppm files
+./build.ts --ppm --minify main.asm > pacman.asm
 ```
 
 ## Documentation