Add support for macOS Universal dylib cross-compilation

README.md

@@ -217,7 +217,8 @@ For example, [monero-java](https://github.com/woodser/monero-java) compiles this
     ```
 4. Build monero-project, located as a submodule at ./external/monero-project. Install [dependencies](https://github.com/monero-project/monero#dependencies) as needed for your system, then build with e.g.: `make release-static -j6`
 5. Link to this library's source files in your application, or build monero-cpp to a shared library in ./build: `./bin/build_libmonero_cpp.sh`
-
+> Note: The above process will only build a native macOS binary dependent on your device's platform. To create a universal binary, use the build.sh script provided in [macos_universal](macos_universal).
+> CAVEATS: This script MUST BE RAN FROM WITHIN THE macos_universal directory. As of writing, the script has only been verified to work properly on a Debian 12 system. In theory, there is nothing stopping the universal binary from being cross-compiled on other platforms, although Windows in particular would require some extra changes in order to work.
 ### Windows
 
 1. Download and install [MSYS2](https://www.msys2.org/).