Drop "tap" langauge for homebrew installation (#125)

Author: joshmedeski

README.md

@@ -59,11 +59,10 @@ Works with all reasonably recent [tmux](https://github.com/tmux/tmux) versions (
 [Download the latest](https://github.com/arl/gitmux/releases/latest) binary for your platform/architecture and uncompress it.
 
 
-### Homebrew tap (macOS and linux) (amd64 and arm64)
+### Homebrew (macOS and linux) (amd64 and arm64)
 
 Install the latest version with:
 
-    brew tap arl/arl
     brew install gitmux
 
 ### AUR