fix: useradd in Running step-ca as a Daemon

Signed-off-by: Kaita Nakamura <kaita.nakamura0830@gmail.com>

Author: z63d

step-ca/certificate-authority-server-production.mdx

@@ -365,8 +365,8 @@ Note: _This section requires a Linux OS running `systemd` version 245 or greater
 
   The service user will only be used by `systemd` to manage the CA. Run:
 
-  <CodeBlock language="shell-session" copytext="sudo useradd --user-group --system --home /etc/step-ca --shell /bin/false step">
-  {`$ sudo useradd --user-group --system --home /etc/step-ca --shell /bin/false step`}
+  <CodeBlock language="shell-session" copytext="sudo useradd --user-group --system --create-home --home /etc/step-ca --shell /bin/false step">
+  {`$ sudo useradd --user-group --system --create-home --home /etc/step-ca --shell /bin/false step`}
   </CodeBlock>
 
   If your CA will bind to port 443, the `step-ca` binary will need to be