Add generated headers to the doc only logic

Author: a-maurice

CMakeLists.txt

@@ -273,7 +273,7 @@ endif()
 if (FIREBASE_INCLUDE_ANALYTICS)
   add_subdirectory(analytics)
   list(APPEND TARGET_LINK_LIB_NAMES "firebase_analytics" "firebase_analytics_swig")
-  list(APPEND DOCUMENTATION_ONLY_LIB_NAMES "firebase_analytics_swig")
+  list(APPEND DOCUMENTATION_ONLY_LIB_NAMES "firebase_analytics_swig" FIREBASE_UNITY_ANALYTICS_GENERATED_FILES)
   list(APPEND PROJECT_LIST_HEADER "  X(Analytics)")
 endif()
 if (FIREBASE_INCLUDE_APP_CHECK)