Typo repair.
diff --git a/PCbuild/readme.txt b/PCbuild/readme.txt
index a0be067..c64267f 100644
--- a/PCbuild/readme.txt
+++ b/PCbuild/readme.txt
@@ -91,7 +91,7 @@
 you're not building on an Alpha box.
 
 
-YOUR OWN EXTENSION DDLs
+YOUR OWN EXTENSION DLLs
 -----------------------
 If you want to create your own extension module DLL, there's an example
 with easy-to-follow instructions in ../PC/example/; read the file