Removing outdated references to toy_builder + mentioning encouraging benchmark results.

Author: FranciscoThiesen

README.md

@@ -49,6 +49,9 @@ int main() {
 
 With ~200 lines of code (as you can see in the [toy_builder.cpp](prototype_playground/toy_builder.cpp)).
 
+As of now, we were able to implement this with ~1k lines of code (and that is including Neon + SSE2 optimizations in [json_escaping.hpp](src/json_escaping.hpp)).
+
+The benchmark results are also pretty encouraging, showing serialization speeds that are 20/30x when compared to [nlohmann](https://github.com/nlohmann/json).
 
 ## Current status
 There are 2 versions of compiler that aim to support the C++ 26 reflection paper.