Fix typo

XCode -> Xcode

Author: weitieda

USAGE.md

@@ -4,7 +4,7 @@
 
 The easist way to use these packages is by creating a project with `Briefcase
 <https://github.com/beeware/briefcase>`__. Briefcase will download pre-compiled
-versions of these support packages, and add them to an XCode project (or
+versions of these support packages, and add them to an Xcode project (or
 pre-build stub application, in the case of macOS).
 
 ## The manual way