Docs: Update Gemini 3 Documentation (#91)

* Update docs.

* Update model docs.

docs/get-started/gemini-3.md

@@ -1,56 +1,37 @@
-# Gemini 3 Pro on Gemini CLI
+# Gemini 3 Pro and Gemini 3 Flash on Gemini CLI
 
-We’re excited to bring Gemini 3 Pro to Gemini CLI. Gemini 3 Pro is **currently
-available** on Gemini CLI to all of the following subscribers:
+Gemini 3 Pro and Gemini 3 Flash are now available on Gemini CLI! Currently, most
+paid customers of Gemini CLI will have access to both Gemini 3 Pro and Gemini 3
+Flash, including the following subscribers:
 
-- Google AI Ultra (except Google AI Ultra for Business).
-- Google AI Pro.
-- Gemini Code Assist Standard (requires
+- Google AI Pro and Google AI Ultra (excluding business customers).
+- Gemini Code Assist Standard and Enterprise (requires
   [administrative enablement](#administrator-instructions)).
-- Gemini Code Assist Enterprise (requires
-  [administrative enablement](#administrator-instructions)).
-- Paid Gemini API key holders.
-- Paid Vertex API key holders.
+- Paid Gemini API and Vertex API key holders.
 
-For **everyone else**, we're gradually expanding access
-[through a waitlist](https://goo.gle/geminicli-waitlist-signup). If you don't
-have one of the listed subscriptions, sign up for the waitlist to access Gemini
-3 Pro once approved.
+For free tier users:
 
-**Note:** Whether you’re automatically granted access or accepted from the
-waitlist, you’ll still need to enable Gemini 3 Pro
-[using the `/settings` command](../cli/settings.md).
+- If you signed up for the waitlist, please check your email for details. We’ve
+  onboarded everyone who signed up to the previously available waitlist.
+- If you were not on our waitlist, we’re rolling out additional access gradually
+  to ensure the experience remains fast and reliable. Stay tuned for more
+  details.
 
-## How to join the waitlist
+## How to get started with Gemini 3 on Gemini CLI
 
-Users not automatically granted access will need to join the waitlist. Follow
-these instructions to sign up:
+Get started by upgrading Gemini CLI to the latest version (0.21.1):
 
-- Install Gemini CLI.
-- Authenticate using the **Login with Google** option. You’ll see a banner that
-  says “Gemini 3 is now available.” If you do not see this banner, update your
-  installation of Gemini CLI to the most recent version.
-- Fill out this Google form:
-  [Access Gemini 3 in Gemini CLI](https://goo.gle/geminicli-waitlist-signup).
-  Provide the email address of the account you used to authenticate with Gemini
-  CLI.
+```bash
+npm install -g @google/gemini-cli@latest
+```
 
-Users will be onboarded in batches, subject to availability. When you’ve been
-granted access to Gemini 3 Pro, you’ll receive an acceptance email to your
-submitted email address.
+After you’ve confirmed your version is 0.21.1 or later:
 
-**Note:** Please wait until you have been approved to use Gemini 3 Pro to enable
-**Preview Features**. If enabled early, the CLI will fallback to Gemini 2.5 Pro.
+1. Use the `/settings` command in Gemini CLI.
+2. Toggle **Preview Features** to `true`.
+3. Run `/model` and select **Auto (Gemini 3)**.
 
-## How to use Gemini 3 Pro with Gemini CLI
-
-Once you receive your acceptance email–or if you are automatically granted
-access–you still need to enable Gemini 3 Pro within Gemini CLI.
-
-To enable Gemini 3 Pro, use the `/settings` command in Gemini CLI and set
-**Preview Features** to `true`.
-
-For more information, see [Gemini CLI Settings](../cli/settings.md).
+For more information, see [Gemini CLI model selection](../cli/model.md).
 
 ### Usage limits and fallback
 
@@ -68,10 +49,10 @@ There may be times when the Gemini 3 Pro model is overloaded. When that happens,
 Gemini CLI will ask you to decide whether you want to keep trying Gemini 3 Pro
 or fallback to Gemini 2.5 Pro.
 
-**Note:** The **Keep trying** option uses exponential backoff, in which Gemini
-CLI waits longer between each retry, when the system is busy. If the retry
-doesn't happen immediately, please wait a few minutes for the request to
-process.
+> **Note:** The **Keep trying** option uses exponential backoff, in which Gemini
+> CLI waits longer between each retry, when the system is busy. If the retry
+> doesn't happen immediately, please wait a few minutes for the request to
+> process.
 
 ### Model selection and routing types
 
@@ -92,7 +73,7 @@ manage your usage limits:
 To learn more about selecting a model and routing, refer to
 [Gemini CLI Model Selection](../cli/model.md).
 
-## How to enable Gemini 3 Pro with Gemini CLI on Gemini Code Assist
+## How to enable Gemini 3 with Gemini CLI on Gemini Code Assist
 
 If you're using Gemini Code Assist Standard or Gemini Code Assist Enterprise,
 enabling Gemini 3 Pro on Gemini CLI requires configuring your release channels.
@@ -123,7 +104,7 @@ then:
 - Use the `/settings` command.
 - Set **Preview Features** to `true`.
 
-Restart Gemini CLI and you should have access to Gemini 3 Pro.
+Restart Gemini CLI and you should have access to Gemini 3.
 
 ## Need help?