xctool: update link (#11165)

pages/osx/xctool.md

@@ -1,7 +1,7 @@
 # xctool
 
 > Tool for building Xcode projects.
-> More information: <https://github.com/facebook/xctool>.
+> More information: <https://github.com/facebookarchive/xctool>.
 
 - Build a single project without any workspace: