Fix grammar in API doc

Co-authored-by: Gio Lodi <giovanni.lodi42@gmail.com>

Author: crazytonyli

WordPress/Classes/Utility/ContextManager.h

@@ -4,7 +4,7 @@
 NS_ASSUME_NONNULL_BEGIN
 
 /**
- A constant representing current version of data model.
+ A constant representing the current version of the data model.
 
  @see -[ContextManager initWithModelName:storeURL:]
  */