Fixed homebrew formula path (#1219)

README.md

@@ -47,7 +47,7 @@ Check the [releases](https://github.com/slackhq/nebula/releases/latest) page for
     $ sudo apk add nebula
     ```
 
-- [macOS Homebrew](https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/nebula.rb)
+- [macOS Homebrew](https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/n/nebula.rb)
     ```
     $ brew install nebula
     ```