add minify flag to build script

(cherry picked from commit f0b43f7b7c)

readme.md

@@ -31,10 +31,7 @@ It also convert the PPM assets (map and sprites) into ASM raw values representat
 
 Usage example:
 ```sh
-./build.ts > /path/to/the/game/schematics/architecture/Symfony/sandbox/main.asm
-
-# script output can easily be piped to strip it off all comments, leading whitespace, double spaces and empty lines:
-./build.ts | sed -r 's/\s*;.*//' | sed -r 's/^\s+//' | sed -r 's/ +/ /' | sed -r '/^\s*$/d' > result.asm
+./build.ts --minify > /path/to/the/game/schematics/architecture/Symfony/sandbox/main.asm
 ```
 
 The script is build over Deno's API, so you'll need to have a `deno` binary in your PATH to use it that way.