Fix CLI reference URLs to subcommands (#5722)

## Summary

Currently all of these links end up 404-ed. I've added a `#` to fix the
URLs.

<img width="653" alt="Screenshot 2024-08-02 at 12 34 22"
src="https://github.com/user-attachments/assets/9b66adcc-431c-441a-8f4f-1b579472fdce">

## Test Plan

Checked manually.

crates/uv-dev/src/generate_cli_reference.rs

@@ -143,7 +143,7 @@ fn generate_command<'a>(output: &mut String, command: &'a Command, parents: &mut
             }
             let subcommand_name = format!("{name} {}", subcommand.get_name());
             output.push_str(&format!(
-                "<dt><a href=\"{}\"><code>{subcommand_name}</code></a></dt>",
+                "<dt><a href=\"#{}\"><code>{subcommand_name}</code></a></dt>",
                 subcommand_name.replace(' ', "-")
             ));
             if let Some(about) = subcommand.get_about() {