fix typo

README.md

@@ -6,13 +6,13 @@
 
 ## Background
 
-[ProDOS 2.4](https://prodos8.com/) includes the [Bitsy Bye](https://prodos8.com/bitsy-bye/) program launcher. It can launch System (SYS), Binary (BIN) and BASIC (BAS) files. For other file types, if there's a `BASIS.SYSTEM` handler in the root volume, it is invoked to handle the file.
+[ProDOS 2.4](https://prodos8.com/) includes the [Bitsy Bye](https://prodos8.com/bitsy-bye/) program launcher. It can launch System (SYS), Binary (BIN) and BASIC (BAS) files. For other file types, if there's a `BASIS.SYSTEM` handler in the root directory of the volume, it is invoked to handle the file.
 
 [DOS 3.3 Launcher](http://apple2.org.za/gswv/a2zine/Docs/Dos33Launcher_Docs.txt) is a tool to run certain DOS 3.3 games (or more commonly, game cracks) under ProDOS. Launchers must be specially configured to invoke it for these DOS 3.3 files (file types $F1, $F2, $F3, $F4).
 
 ## What's this?
 
-This repro includes a `BASIS.SYSTEM` implementation that takes the passed file and invokes `DOS3.3.LAUNCHER` on it. It searches for `DOS3.3.LAUNCHER` starting in the directory containing the DOS 3.3 file, and then upwards. So you can create a disk like this:
+This repo includes a `BASIS.SYSTEM` implementation that takes the passed file and invokes `DOS3.3.LAUNCHER` on it. It searches for `DOS3.3.LAUNCHER` starting in the directory containing the DOS 3.3 file, and then upwards. So you can create a disk like this:
 
 * `PRODOS`
 * `QUIT.SYSTEM`