Add Homebrew installation step to README.md

Author: bahlo

README.md

@@ -11,6 +11,12 @@ A terminal UI that scrapes host metrics with the upstream OpenTelemetry
 
 ## Install
 
+With Homebrew:
+
+```sh
+brew install axiomhq/tap/axiom-hostmetrics
+```
+
 Build from source (Go 1.22+):
 
 ```sh