Update README

README.md

@@ -5,9 +5,12 @@ Disassemblies of Landstalker ROMs
 ## Build instructions
 
 - Run the `build.bat` (Windows) or `build.sh` (Linux) script - this will assemble the previously disassembled files. If no changes have been made to the disassembly, you should end up with a file identical to the US release ROM.
-- Run the `build_expanded.bat` (Windows) or `build_expanded.sh` (Linux) script to build an expanded 4MByte rom, functionally equivalent to the original US ROM but with plenty of additional space for new content.
+- The following command line parameters can be passed to the build script:
+    - `-r`: Specify ROM region. Can be one of 'JP', 'US'.
+    - `-e`: Build a 4MByte expanded ROM. This increases the size of the ROM to 4 Megabytes, significantly increasing the available storage space for modifications.
+    - `-o`: Specify the output ROM filename.
 
-Note: Linux users will need to install wine in order to build the ROM.
+Note: Linux users will need to install wine in order to build the ROM. Python is required for generating the ROM checksum.
 
 Enjoy!