fw/applib/app_sync: fix documentation comments

The generate_native_sdk script was getting confused, and thought those comments
were documentation for the AppSync struct, leading to it including those
comments in the generated pebble.h file verbatim. This resulted in closing
Doxygen groups earlier than they should have been, and excluding a large portion
of the documentation from generated docs.

Signed-off-by: Ruby Iris Juric <ruby@srxl.me>

src/fw/applib/app_sync/app_sync.h

@@ -145,10 +145,6 @@ AppMessageResult app_sync_set(struct AppSync *s, const Tuplet * const keys_and_v
 //! specified key.
 const Tuple * app_sync_get(const struct AppSync *s, const uint32_t key);
 
-
-//!   @} // end addtogroup AppSync
-//! @} // end addtogroup Foundation
-
 typedef struct AppSync {
   DictionaryIterator current_iter;
   union {
@@ -162,3 +158,6 @@ typedef struct AppSync {
     void *context;
   } callback;
 } AppSync;
+
+//!   @} // end addtogroup AppSync
+//! @} // end addtogroup Foundation