docs(readme): refresh Gemini CLI section to reflect v0.0.11 hook fix (#31)

The Gemini CLI install instructions were a vague one-liner pointing
at the Install section to install the binary manually first. With
v0.0.11 the SessionStart hook is portable across Claude Code and
Gemini CLI, so the binary auto-installs on the first session under
Gemini exactly as it does under Claude.

- Show the actual 'gemini extension install' command users should run.
- Note the GitHub-Releases-asset 404 fallthrough and the 'git clone'
  fallback prompt (matches what users see today and what the docs
  hub gemini-cli.md describes).
- State that the same SessionStart hook handles binary install and
  version pinning under Gemini — no manual install needed.

Signed-off-by: Ben <ben@armosec.io>

Author: slashben

README.md

@@ -17,7 +17,11 @@ The first time a session starts, the plugin checks for the `armoctl` binary on `
 
 ### Gemini CLI
 
-Add this repo as an extension. The Gemini extension loads the same skills as the Claude plugin from `skills/`. Install the binary first (see the next section).
+```
+gemini extension install https://github.com/armosec/armoctl
+```
+
+Gemini CLI first tries to fetch a release-asset bundle and fails with a 404, then offers a `git clone` fallback — answer **Y** to that prompt and accept the one-time review of hooks/skills. The extension loads the same skills as the Claude plugin and the same SessionStart hook installs/updates the `armoctl` binary on the first session. No need to install the binary manually first.
 
 ### What's in the plugin