docs: remove deprecated Homebrew tap step (#4319)

docs/user-manual/en/1-getting-started/1.2-installation.md

@@ -122,9 +122,6 @@ npm install -g @google/gemini-cli
 ### Option 1: Homebrew (Recommended)
 
 ```bash
-# Add tap
-brew tap farion1231/ccswitch
-
 # Install
 brew install --cask cc-switch
 ```

docs/user-manual/ja/1-getting-started/1.2-installation.md

@@ -122,9 +122,6 @@ npm install -g @google/gemini-cli
 ### 方法 1：Homebrew（推奨）
 
 ```bash
-# tap を追加
-brew tap farion1231/ccswitch
-
 # インストール
 brew install --cask cc-switch
 ```

docs/user-manual/zh/1-getting-started/1.2-installation.md

@@ -138,9 +138,6 @@ npm install -g @google/gemini-cli --registry=https://registry.npmmirror.com
 ### 方式一：Homebrew（推荐）
 
 ```bash
-# 添加 tap
-brew tap farion1231/ccswitch
-
 # 安装
 brew install --cask cc-switch
 ```