Move documentation from Path.cpp to Path.dox

And clean it up a bit. Kept brief description in source.
* Also added Axel to authors in Path.dox and Path.cpp because his name
  appears in git blame as working on the docs and code for the file.
  I hope he doesn't mind.

headers/os/storage/Path.h

@@ -76,7 +76,9 @@ private:
 			uint32			_reserved[4];
 
 			char*			fName;
+								// Pointer to the path string of the object.
 			status_t		fCStatus;
+								// The initialization status of the object.
 };
 
 #endif	// _PATH_H