📝 add more docs (#5231)

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

docs/mkdocs/docs/api/basic_json/format_as.md

@@ -88,6 +88,7 @@ std::string format_as(const BasicJsonType& j)
 
 - [dump](dump.md)
 - [std::formatter<basic_json>](std_formatter.md) - the `std::format` (C++20) equivalent
+- [Serialization](../../features/serialization.md) - the serialization article
 
 ## Version history