Document supported datatypes

README.md

@@ -10,6 +10,29 @@ This repository also contains a small, additional header to use RapidJSON with B
 or dezerialize simple data structures using the `BOOST_HANA_DEFINE_STRUCT` macro rather than requiring the code
 generator.
 
+## Supported datatypes
+The following table shows the mapping of supported C++ types to supported JSON types:
+
+| C++ type                                 | JSON type |
+| ---------------------------------------- |:---------:|
+| custom structures/classes                | object    |
+| bool                                     | true/false|
+| signed and unsigned integral types       | number    |
+| float and double                         | number    |
+| enum and enum class                      | number    |
+| std::string                              | string    |
+| const char *                             | string    |
+| iteratables (std::vector, std::list, ...)| array     |
+| std::tuple                               | array     |
+
+### Remarks
+* `const char *` is only supported for serialization.
+* Enums are only supported for serialization.
+* For deserialization, iteratables must provide an `emplace_back` method. So deserialization of eg. `std::forward_list`
+  is currently not supported.
+* Using pointers is not supported yet.
+* The JSON type `null` is not supported yet.
+
 ## Usage
 This example shows how the library can be used to make a `struct` serializable:
 ```