Fix URL to load code with Metacello

Author: koendehondt

README.md

@@ -1,13 +1,13 @@
 # CodeOfSpec20Book
 
-This repository contains example code for the Spec 2.0 framework and is a companion for the book [Application Building with Spec 2.0](https://github.com/SquareBracketAssociates/BuildingApplicationWithSpec2), 
+This repository contains example code for the Spec 2.0 framework and is a companion for the book [Application Building with Spec 2.0](https://github.com/SquareBracketAssociates/BuildingApplicationWithSpec2),
 describing in detail the Pharo framework to build user interfaces.
 
 To load it:
 
 ```smalltalk
 Metacello new
     baseline: 'CodeOfSpec20Book';
-    repository: 'github://SquareBracketAssociates/CodeOfSpec20Book/src';
+    repository: 'github://SquareBracketAssociates/CodeOfSpec20Book:master/src';
     load
 ```