Update project description

Author: fwcd

README.md

@@ -3,9 +3,9 @@
 [![Build](https://github.com/fwcd/swift-static-map/actions/workflows/build.yml/badge.svg)](https://github.com/fwcd/swift-static-map/actions/workflows/build.yml)
 [![Docs](https://github.com/fwcd/swift-static-map/actions/workflows/docs.yml/badge.svg)](https://fwcd.github.io/swift-static-map/documentation/staticmap)
 
-A small library for generating static maps directly from [OpenStreetMap](https://www.openstreetmap.org) tiles.
+A small, pure Swift library for generating static maps directly from [OpenStreetMap](https://www.openstreetmap.org) tiles.
 
-The implementation is based on a port of [danielalvsaaker](https://github.com/danielalvsaaker)'s [`staticmap`](https://github.com/danielalvsaaker/staticmap) library for Rust.
+The implementation is based on a port of [danielalvsaaker](https://github.com/danielalvsaaker)'s [`staticmap`](https://github.com/danielalvsaaker/staticmap) library for Rust and supports both Linux and macOS.
 
 ## Examples