Emphasize official Gemini CLI documentation link

Reduce detailed installation steps and direct users to official docs for
up-to-date instructions, addressing reviewer feedback about maintainability.

Author: ipapapa

docs/installation-guides/install-gemini-cli.md

@@ -7,23 +7,20 @@
 
 ## Installation Options
 
-### Option 1: npm (Global Installation)
+Install Google Gemini CLI using your preferred method. For the most up-to-date installation instructions and troubleshooting, see the [official Gemini CLI documentation](https://github.com/google-gemini/gemini-cli).
+
+### Quick Install Options
 ```bash
+# npm (Global Installation)
 npm install -g @google/gemini-cli
-```
 
-### Option 2: npx (No Installation Required)
-```bash
+# npx (No Installation Required)
 npx @google/gemini-cli
-```
 
-### Option 3: Homebrew
-```bash
+# Homebrew
 brew install gemini-cli
 ```
 
-For more detailed installation instructions, see the [official Gemini CLI documentation](https://github.com/google-gemini/gemini-cli).
-
 ## Authentication Setup
 
 Before using Gemini CLI, you need to authenticate with Google: