Update comment generator to apply to maps

Change comment from "array" to "container" because sometimes it's a map.

src/google/protobuf/compiler/objectivec/objectivec_field.cc

@@ -388,7 +388,7 @@ void RepeatedFieldGenerator::GeneratePropertyDeclaration(
       "$comments$"
       "$array_comment$"
       "@property(nonatomic, readwrite, strong, null_resettable) $array_property_type$ *$name$$storage_attribute$$deprecated_attribute$;\n"
-      "/** The number of items in @c $name$ without causing the array to be created. */\n"
+      "/** The number of items in @c $name$ without causing the container to be created. */\n"
       "@property(nonatomic, readonly) NSUInteger $name$_Count$deprecated_attribute$;\n");
   if (IsInitName(variables_.find("name")->second)) {
     // If property name starts with init we need to annotate it to get past ARC.