feat(brew): autoconfigure completions (#11152)

plugins/brew/README.md

@@ -33,6 +33,8 @@ defined for convenience.
 
 ## Completion
 
+This plugin configures paths with Homebrew's completion functions automatically, so you don't need to do it manually. See: https://docs.brew.sh/Shell-Completion#configuring-completions-in-zsh.
+
 With the release of Homebrew 1.0, they decided to bundle the zsh completion as part of the
 brew installation, so we no longer ship it with the brew plugin; now it only has brew
 aliases. If you find that brew completion no longer works, make sure you have your Homebrew

plugins/brew/brew.plugin.zsh

@@ -25,6 +25,10 @@ if [[ -z "$HOMEBREW_PREFIX" ]]; then
   export HOMEBREW_PREFIX="$(brew --prefix)"
 fi
 
+if [[ -d "$HOMEBREW_PREFIX/share/zsh/site-functions" ]]; then
+  fpath+=("$HOMEBREW_PREFIX/share/zsh/site-functions")
+fi
+
 alias bcubc='brew upgrade --cask && brew cleanup'
 alias bcubo='brew update && brew outdated --cask'
 alias bcubc='brew upgrade --cask && brew cleanup'