📝 comment how to integrate fifo_map (#485)

Author: nlohmann

README.md

@@ -924,7 +924,7 @@ The library is currently used in Apple macOS Sierra and iOS 10. I am not sure wh
   - The strings stored in the library are UTF-8 encoded. When using the default string type (`std::string`), note that its length/size functions return the number of stored bytes rather than the number of characters or glyphs.
 - The code can be compiled without C++ **runtime type identification** features; that is, you can use the `-fno-rtti` compiler flag.
 - **Exceptions** are used widely within the library. They can, however, be switched off with either using the compiler flag `-fno-exceptions` or by defining the symbol `JSON_NOEXCEPTION`. In this case, exceptions are replaced by an `abort()` call.
-- By default, the library does not preserve the **insertion order of object elements**. This is standards-compliant, as the [JSON standard](https://tools.ietf.org/html/rfc7159.html) defines objects as "an unordered collection of zero or more name/value pairs". If you do want to preserve the insertion order, you can specialize the object type with containers like [`tsl::ordered_map`](https://github.com/Tessil/ordered-map) or [`nlohmann::fifo_map`](https://github.com/nlohmann/fifo_map).
+- By default, the library does not preserve the **insertion order of object elements**. This is standards-compliant, as the [JSON standard](https://tools.ietf.org/html/rfc7159.html) defines objects as "an unordered collection of zero or more name/value pairs". If you do want to preserve the insertion order, you can specialize the object type with containers like [`tsl::ordered_map`](https://github.com/Tessil/ordered-map) or [`nlohmann::fifo_map`](https://github.com/nlohmann/fifo_map) (see [this comment](https://github.com/nlohmann/json/issues/485#issuecomment-333652309) on how to integrate).
 
 
 ## Execute unit tests