docs: use simpler curl and irm for Codex installation in README

Author: belluru

README.md

@@ -45,12 +45,12 @@ gemini extensions install https://github.com/gemini-cli-extensions/data-cloud-ai
 #### Codex
 **macOS / Linux:**
 ```bash
-gh api repos/gemini-cli-extensions/data-cloud-ai-dev-kit/contents/codex-install.sh -H "Accept: application/vnd.github.raw" | bash
+curl -sSL https://raw.githubusercontent.com/gemini-cli-extensions/data-cloud-extension/main/codex-install.sh | bash
 ```
 
 **Windows:**
 ```powershell
-gh api repos/gemini-cli-extensions/data-cloud-extension/contents/codex-install.ps1 -H "Accept: application/vnd.github.raw" | powershell -ExecutionPolicy Bypass -
+irm https://raw.githubusercontent.com/gemini-cli-extensions/data-cloud-extension/main/codex-install.ps1 | iex
 ```
 
 ## Usage Examples