Add --fernie flag to CLI reference for emailing both co-founders

Introduced the --fernie flag that allows users to send emails to both Deep and
Danny simultaneously. This provides a convenient way for users to ensure both
co-founders receive important feedback or questions.

Changes include:
- Added --fernie to the main commands table
- Created comprehensive accordion documentation section
- Documented all three options: --message, --subject, and --respond_to
- Provided usage examples for contacting both founders
- Added helpful tip explaining when to use --fernie

The documentation follows the same pattern as --dsinghvi and --dsheridan for
consistency across all co-founder contact commands.

Author: fern-support

fern/products/cli-api-reference/pages/commands.mdx

@@ -16,6 +16,7 @@ hideOnThisPage: true
 | [`fern api update`](#fern-api-update) | Manually update your OpenAPI spec |
 | [`fern --dsinghvi`](#fern---dsinghvi) | Send an email to Deep, our co-founder |
 | [`fern --dsheridan`](#fern---dsheridan) | Send an email to Danny, our co-founder |
+| [`fern --fernie`](#fern---fernie) | Send an email to both co-founders |
 
 ## Documentation commands
 
@@ -699,4 +700,59 @@ hideOnThisPage: true
     </Tip>
 
   </Accordion>
+
+  <Accordion title="fern --fernie">
+
+    Use `fern --fernie` to send an email to both Deep and Danny, our co-founders. This is perfect when you want to ensure both founders see your feedback, questions, or ideas!
+
+    <CodeBlock title="terminal">
+    ```bash
+    fern --fernie [--message <your-message>] [--subject <subject>] [--respond_to <email>]
+    ```
+    </CodeBlock>
+
+    When run without options, this command will open your default email client with a pre-addressed message to both co-founders.
+
+    ### message
+
+    Use `--message` to include a specific message in your email.
+
+    ```bash
+    fern --fernie --message "Love the new SDK generation features!"
+    ```
+
+    ### subject
+
+    Use `--subject` to set a custom subject line for your email.
+
+    ```bash
+    fern --fernie --subject "Feature Request: GraphQL Support"
+    ```
+
+    ### respond_to
+
+    Use `--respond_to` to provide your email address so the co-founders can respond to you.
+
+    ```bash
+    fern --fernie --respond_to "[email protected]"
+    ```
+
+    ### Example usage
+
+    ```bash
+    # Open email client
+    fern --fernie
+
+    # Send a quick message to both founders
+    fern --fernie --message "Thanks for building Fern!" --respond_to "[email protected]"
+
+    # Send detailed feedback with all options
+    fern --fernie --subject "Product Feedback" --message "The entire platform is amazing!" --respond_to "[email protected]"
+    ```
+
+    <Tip>
+    Use `--fernie` when you want both Deep and Danny to see your message. They love hearing from the community!
+    </Tip>
+
+  </Accordion>
 </AccordionGroup>