update README

Author: sbeamer

README.md

@@ -1,7 +1,7 @@
 RISC-V Toolchain [![Build Status](https://github.com/riscv/homebrew-riscv/actions/workflows/macos-ci.yml/badge.svg)](https://github.com/riscv/homebrew-riscv/actions/workflows/macos-ci.yml)
 ================
 
-This provides packages to install the [RISC-V](http://riscv.org) toolchain on OS X using [Homebrew](http://brew.sh).
+This provides packages to install the [RISC-V](http://riscv.org) toolchain on macOS using [Homebrew](http://brew.sh).
 
 
 Installation