doc: add yaml-cpp to dependency list

doc/setup.md

@@ -38,6 +38,10 @@ This includes [`ninja`](https://ninja-build.org/), which `meson` will benefit fr
   - If you need Python bindings on macOS, please install `fmt` with `brew install fmt`
   - If you compile it yourself on Linux, include the `cmake` option `-DCMAKE_POSITION_INDEPENDENT_CODE=ON` to build the static library
 
+### 🔶 `yaml-cpp`: YAML parser and emitter
+<https://github.com/jbeder/yaml-cpp>
+- Likely available in your package manager, likely as `yaml-cpp`
+
 ### 🔶 `hipo`: C++ HIPO API
 <https://github.com/gavalian/hipo>
 - Use the `hipo` module on `ifarm`, or obtain and build it yourself