fix(docs): Update macos GCC embedded section with brew cmd

* Update macos GCC embedded section with brew cmd

Brew has a cask for GCC embedded, so we can make this guide more user friendly by providing it.

docs/docs/development/setup.md

@@ -337,6 +337,12 @@ Since the Zephyr™ SDK is not available for Windows, we recommending following
 
 Since the Zephyr™ SDK is not available for macOS, we recommending following the steps to install the [GNU ARM Embedded](https://docs.zephyrproject.org/2.3.0/getting_started/toolchain_3rd_party_x_compilers.html#gnu-arm-embedded).
 
+The install command is:
+
+```
+brew install --cask gcc-arm-embedded
+```
+
 :::warning Security Controls Workaround
 
 Please be sure to read the [additional setup instructions](https://docs.zephyrproject.org/2.3.0/getting_started/installation_mac.html#mac-gatekeeper) needed to address security controls found in macOS 10.15 Catalina and newer