Add fern deep command to CLI reference

This adds documentation for the new `fern deep` command that allows users to email Deep, our co-founder. The command supports optional --message and --subject flags, or can be run interactively without arguments.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: fern-support

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

@@ -14,6 +14,7 @@ hideOnThisPage: true
 | [`fern logout`](#fern-logout) | Log out of the Fern CLI |
 | [`fern export`](#fern-export) | Export an OpenAPI spec for your API |
 | [`fern api update`](#fern-api-update) | Manually update your OpenAPI spec |
+| [`fern deep`](#fern-deep) | Email Deep, our co-founder |
 
 ## Documentation commands
 
@@ -579,12 +580,45 @@ hideOnThisPage: true
 
   ### api
 
-  Use `--api` to specify the API to update if there are multiple specs with a defined `origin` in `generators.yml`. If you don't specify an API, all OpenAPI specs with an `origin` will be updated. 
+  Use `--api` to specify the API to update if there are multiple specs with a defined `origin` in `generators.yml`. If you don't specify an API, all OpenAPI specs with an `origin` will be updated.
 
   <CodeBlock title="terminal">
     ```bash
     fern api update --api public-api
     ```
   </CodeBlock>
   </Accordion>
+
+  <Accordion title="fern deep">
+
+    Use `fern deep` to send an email directly to Deep, our co-founder. This command is useful when
+    you need to reach out with feedback, questions, or suggestions about Fern.
+
+    <CodeBlock title="terminal">
+    ```bash
+    fern deep [--message <message>] [--subject <subject>]
+    ```
+    </CodeBlock>
+
+    ### message
+
+    Use `--message` to include a message in your email to Deep.
+
+    ```bash
+    fern deep --message "Love the new CLI features!"
+    ```
+
+    ### subject
+
+    Use `--subject` to specify a custom subject line for your email.
+
+    ```bash
+    fern deep --subject "Feature Request" --message "It would be great to have..."
+    ```
+
+    <Tip>
+    You can also run `fern deep` without any arguments to compose your email interactively.
+    </Tip>
+
+  </Accordion>
 </AccordionGroup>